Measles

April

Full chapter update to the new format. Includes changes to the following sections.

• Epidemiology – new subsection for global epidemiology and update to information in the Aotearoa New Zealand epidemiology subsection.
• At risk and priority populations – new section
• The disease – new section
• Spread of infection – new subsections for reservoir and infection prevention and control and updated to information in the incubation period, mode of transmission and infectious period.
• Routine prevention – new section
• Notification and reporting – new subsections for national escalation and international reporting.
• Case management – new subsections for public health priority and Manaakitanga/Manaaki in practice and updated guidance on investigation, isolation, monitoring, and treatment. Key changes include clearer criteria for diagnosis, risk assessment, and release from isolation.
• Contact management – new subsections for Manaakitanga/Manaaki in practice and public health priority and additional information added for hospitalised close contacts.
• Exposure event management – new section
• Outbreaks – new section

November

• Case definition – new subsections for epidemiological criteria and laboratory criteria. Clinical description subsection heading changed to clinical criteria.
• Laboratory testing – new section
• Contact management – new subsection for post-exposure prophylaxis.

July

• Contact management – section update to the new format and updates to advice on the management of partially vaccinated contacts, extending symptom monitoring to the full 21-day incubation period, the definition of a casual contact and guidance on serology testing for contacts.

Before the introduction of a measles vaccine in 1963 and subsequent widespread vaccination, major epidemics occurred approximately every 2 to 3 years and caused an estimated 2.6 million deaths each year [1]. Although measles mortality rates have fallen significantly since the introduction of the measles mumps and rubella (MMR) vaccine [2], measles remains a significant vaccine-preventable cause of death among children throughout the world, particularly in low-income countries in Africa and Asia. For information on reported cases of measles by country, refer to WHO - Measles - Reported cases and incidence (external link).

More recently the global measles situation has worsened with a resurgence of measles cases, primarily driven by a decline in vaccination rates compounded by misinformation, vaccine hesitancy and variable access to healthcare.

The global resurgence in measles cases, particularly in areas with large outbreaks such as South-East Asia where there is frequent travel to and from Aotearoa New Zealand, increases the risk of measles introductions into Aotearoa New Zealand.

For more detailed information on the number of reported measles cases globally, visit the World Health Organization's measles data webpage (external link).

In 2017, the World Health Organization verified that Aotearoa New Zealand had eliminated measles [3].

In 2019, Aotearoa New Zealand experienced its largest measles outbreak since 1997, following multiple virus introductions, with 2,185 cases notified across the country. The outbreak started in February 2019 and lasted more than a year. Most cases were reported in the Auckland region. Māori and Pacific populations were disproportionately affected with incidences 4 and 14 times (respectively) greater than that of the New Zealand European population. Almost 70% of cases had never been vaccinated and 35% of cases were hospitalised [4]. This outbreak also triggered a major outbreak in Samoa where the incidence rate was around 10 times that of Aotearoa New Zealand, with one-third of cases hospitalised and 83 deaths [5].

Between January 2023 and January 2025, 15 measles cases were notified. This included a single outbreak of 9 cases.

To prevent widespread transmission, 95% of the population need to be immune to measles which requires 2 MMR vaccinations. In Aotearoa New Zealand, overall coverage rates in children for the second measles, mumps, rubella vaccination (MMR2) declined from 91% in 2020 to 84% in 2023 [6]. Vaccination coverage varies substantially by region and ethnicity due to several factors including systemic barriers to access to vaccination and healthcare in general [7].

High rates of international travel, an increase in the number of measles cases globally, a decline in childhood MMR vaccination rates and known immunity gaps in adults mean that Aotearoa New Zealand is at high risk of a large outbreak. Due to the variation in MMR vaccination coverage, an outbreak is likely to disproportionately impact Māori and Pacific communities.

Refer to the ESR Measles dashboard (external link) and the Immunisation Handbook measles chapter for further information on the epidemiology of measles in Aotearoa New Zealand.

Anyone who is not immune to measles is at risk of infection. Protection from measles is primarily due to humoral (antibody-based) immunity which develops following infection or vaccination.

In Aotearoa New Zealand the following demographic groups experience the lowest immunity to measles and therefore have the highest risk of infection if exposed to measles [8.9].

• Infants aged under 12 months (who are too young to be vaccinated).
• Māori [10,11].
• Pacific Peoples [10,11].
• Individuals living in socioeconomically deprived communities (deciles 9 and 10).

Impact of immunosuppression on immunity to measles

Individuals with the following conditions may lose or not maintain their immunity and will be at higher risk of infection if exposed to measles [12].

• Patients on or after completion of immunosuppressive chemotherapy for acute lymphoblastic leukaemia (all).
• Patients with lymphoproliferative disorders (including haematological malignancies such as indolent lymphoma, leukaemia and plasma cell lymphoma).
• Patients who have received a solid organ transplant.
• Patients more than 12 months after receiving a haematopoietic stem cell transplant
• Patients receiving or within 6 months of completing biological therapies (alone or in combination with steroids), these include:
  • monoclonal antibodies (e.g. alemtuzumab, ofatumumab)
  • rituximab cytokine inhibitors (e.g. etanercept).
• Patients with a diagnosis of acquired immunodeficiency syndrome (AIDS).

Groups at low risk of measles infection

Anyone born or living in Aotearoa New Zealand before 1 January 1969 is assumed to be immune. This is because measles is so infectious that before the vaccine was introduced, almost everyone was infected in childhood.

However, individuals born in countries where the measles vaccine was introduced before 1969 may not be immune to measles. For further information on assessing immunity, refer to Classification of contacts by immune status.

Measles is a serious illness for people of any age and severe illness can occur in people who were previously healthy, with no risk factors [8,13]. International data indicates that groups with a higher risk of developing severe illness from measles complications were [10,13]:

• children aged under 5 years, particularly if they are severely malnourished with Vitamin A deficiency
• adults aged over 20 years
• pregnant
• individuals experiencing immunosuppression. Patients at highest risk include those who have severely impaired cell-mediated immunity, such as patients who have recently undergone bone marrow transplantation, patients with primary T-cell dysfunction, AIDS patients and patients with acute lymphoblastic leukaemia [14].

In Aotearoa New Zealand, groups who were more likely to develop severe illness requiring hospitalisation during the 2019/2020 measles outbreak [4,14]:

• children aged under 5 years
• pregnant and up to 6 weeks post-partum
• Māori and Pacific Peoples (in all affected age groups).

Eligibility for post-exposure immunoglobulin prophylaxis

Close contacts at higher risk of severe illness may be eligible for post-exposure immunoglobulin prophylaxis to attenuate measles illness. Public health services should be aware immunoglobulin is not recommended for all the groups described above. Refer to the eligibility criteria). 

As cases increase in the community, the following occupational groups may be more likely to be exposed to measles at work.

• Healthcare workers: barriers to accessing primary care mean cases may be more likely to present to emergency departments and urgent care facilities.
• School/early childhood education staff.

Cases and close contacts (non-immune or partially vaccinated) who work in settings where measles could spread easily and/or where there are individuals at risk of severe illness should be prioritised for public health management. This includes staff working in:

• healthcare settings
• education settings
• correctional facilities
• institutional facilities.

The goal of public health action for measles is to prevent and control outbreaks and minimise the impact of measles on whānau, the community and the health system. 

To achieve this goal and enable an effective and equitable outbreak response, public health action should be prioritised for Māori, Pacific Peoples and socioeconomically deprived communities who have historically experienced a disproportionate burden of measles infection, severe disease and impacts of isolation/quarantine [4,10,11].

This approach is supported by recent measles outbreak modelling which showed that in the event of an outbreak, prioritising Māori and Pacific communities for vaccination could reduce both the number of measles-related hospitalisations and transmission chains within these communities [14].

Impact of disability on burden of measles

The link between disability and measles has not been well explored. However, due to the wide-ranging inequities in accessing healthcare, including vaccination, it is likely that tāngata whaikaha | disabled people will experience a greater burden of measles compared to non-disabled people.

Households with disabled children are more likely to experience socioeconomic disadvantage, and Māori and Pacific children have higher rates of disability (compared to non-Māori, non-Pacific children), which may increase their risk [16]. Children with disabilities may also face additional barriers to vaccination and healthcare [17].

Communicating about measles risk

A person’s risk of developing measles is influenced by their access to measles vaccination, and their risk of severe illness is influenced by their access to health care. In turn these are influenced by a range of factors, including their access to the social determinants of health. Access to these determinants is highly patterned by ethnicity and socioeconomic status, which creates significant inequities in measles vaccination rates for Māori and Pacific Peoples in Aotearoa New Zealand. Working to achieve the health sector principles of the Pae Ora Act is key to overcoming these inequities. 

When discussing the higher burden of measles on Māori, Pacific and socioeconomically deprived communities, it is important to acknowledge the systemic inequities, that create and perpetuate their exposure to risk factors for measles infection and severe illness. Most importantly, public health services must ensure whānau are not unfairly held responsible for circumstances shaped by these wider determinants, including their exposure to specific risk factors. 

For further information on providing culturally safe and equitable care for a range of population groups, refer to the Equity chapter.

For further information on public health service responsibilities under Te Tiriti o Waitangi, refer to Te Tiriti o Waitangi and Māori health.

Measles is an acute respiratory illness caused by the measles virus. Measles is considered the most infectious viral illness transmitted through the respiratory route [18]. 

Classic presentation

Prodromal phase

Measles begins with a prodromal flu-like illness consisting of fever, coryza, cough and conjunctivitis [19]. This usually begins 10 to 14 days after exposure to the virus. Other symptoms such as anorexia, diarrhoea (especially in infants) and generalised lymphadenopathy may also occur during this phase.

Koplik spots (small spots with white or bluish-white lesions, of about 2 to 3mm in diameter, which occur on the cheek mucosa) develop one day before the rash and last for 2 to 3 days after the rash appears. Koplik spots are considered pathognomonic (highly predictive) for measles. However, they can be difficult to identify correctly for clinicians with limited experience of measles.  

Rash phase

Measles rash appears 3 to 5 days after the first symptoms. The fever is always present at the time of rash onset and may peak around this time (generally over 39°C) before gradually decreasing (Figure 1).

The rash is red and maculopapular (appears as flat spots or raised bumps), not itchy and does not form vesicles (fluid or pus-filled bumps). It may be difficult to see on darker skin tones. The spots may appear hyperpigmented, instead of red, with darker or purple macules and papules. 

The rash generally starts on the face, initially at the hairline or behind the ears, before spreading downwards to the neck, trunk and the rest of the body. The number of lesions/spots generally increase in the first 2 to 3 days before starting to fade. 

Convalescent phase

The rash usually resolves after 7 days [20]. Lesions can become confluent, particularly on the face and the trunk. The cough may persist for around 10 days [21].

The measles rash occurs as part of the immune response to the measles virus and therefore may not be present or may present atypically in those who are immunosuppressed or have previously been vaccinated.

Humans are the only reservoir for the measles virus.

The incubation period for measles is approximately:

• 10 days (range 7 to 18 days) from exposure to onset of fever
• 14 days (range 7 to 21 days) from exposure to the onset of rash.

The incubation period may be longer in those given immunoglobulin after exposure. Therefore, quarantine should be extended by 4 days for close contacts who have received post-exposure immunoglobulin prophylaxis.

Measles is transmitted person-to-person by [31]:

• direct contact with infectious droplets (nasal, respiratory or throat)
• airborne spread when an infected person breathes, coughs, or sneezes.

Measles virus can remain infectious in the air or on surfaces for up to 2 hours.

The virus is rapidly inactivated by heat, sunlight and pH extremes [31].

Measles is highly infectious, with a basic reproduction number of approximately 12 to 18. This means a single case can infect 12 to 18 individuals in a completely susceptible (non-immune) population [32]. The secondary attack rate is estimated to be more than 90% among susceptible (non-immune) household and institutional contacts [33].

A case is considered infectious from 4 days before the appearance of rash to 4 full days after the onset of rash, counting the day of rash onset as day 0 (i.e. a total of 9 days).

Community

Cases (confirmed, probable and suspected) in isolation and close contacts who are quarantining/restricted should be advised of appropriate precautions to prevent transmission to others in their household.  

Cases and contacts should be advised to wear a medical or N95/P2 mask around other people in their household and avoid contact with any household members who are not immune to measles. Handwashing and regular cleaning of hard surfaces is recommended. Opening windows to ventilate a room is encouraged but may not be sufficient to prevent transmission.

Cases and close contacts who require medical care should be advised to phone ahead so the facility can take action to prevent transmission (refer to Healthcare settings (external link)) and to wear a medical or N95/P2 mask.

Public health staff visiting cases or contacts at home should follow the infection, prevention and control recommendations for healthcare settings below.

For more information refer to Appendix 6: Infection, prevention and control guidance.

Healthcare settings

Confirmed, probable and suspected cases of measles should be promptly isolated and placed in a single room. Staff should follow standard and airborne precautions. 

Ensure all staff who enter the room are immune to measles and wearing a seal checked N95/P2 mask. After the consultation, leave the room vacant with the door closed for at least 1 hour (or a timeframe directed by the local infection prevention and control team based on air handling and consideration of the potential for the virus to remain viable for up to 2 hours) [34].

Cohorting of patients with the same diagnosis is acceptable.

For more information refer to Infection prevention and control – Health New Zealand | Te Whatu Ora and Measles – Health New Zealand | Te Whatu Ora

Vaccination is the most effective method for preventing measles. The measles, mumps and rubella (MMR) vaccine is highly effective at preventing infection and transmission.

Because of the high transmissibility of measles, 95% of the population must have received two measles containing vaccines to obtain sufficient herd immunity to prevent and contain outbreaks of measles and maintain elimination in Aotearoa New Zealand [35].

A 2-dose MMR vaccination schedule is recommended and is included on the National Immunisation Schedule (external link) at 12 months and 15 months [28].  

A 2-dose schedule is required as up to 10% of people do not develop protective immunity after one MMR vaccine [39,40,41]. The second MMR vaccine is not a booster. Its purpose is to stimulate an immune response in those who did not develop immunity after the first MMR vaccine [2]. After a second dose of MMR vaccine, the proportion of people not protected from measles will be less than 1%.

People born in Aotearoa New Zealand in 1969 or later who do not have documented immunity are advised to get 2 doses of the MMR vaccine, spaced at least 4 weeks apart, unless there are contraindications (e.g. pregnancy and some conditions associated with immunosuppression). Those who have previously received one dose should be advised to get a second dose [35].

MMR vaccination is free for all:

• children under 18 years in New Zealand
• adults aged 18 and over who are eligible for free New Zealand healthcare.

More information on checking for evidence of measles immunity is available in the contact management section and on the Measles immunity (external link) page.

For further information on measles immunisation, including information on eligibility, efficacy and contraindications to vaccination, refer to the Immunisation Handbook - Measles Chapter (external link) and National Immunisation Schedule (external link).

For information on infection, prevention and control refer to the infection, prevention and control subsection and Appendix 6.

Confirmed: A person who has a clinically compatible illness AND has laboratory definitive evidence OR has an epidemiological link to a confirmed case.

Probable: A person who has a clinically compatible illness where there is a high index of suspicion* AND has laboratory suggestive evidence OR laboratory testing is inconclusive or cannot be performed.

*A high index of suspicion includes all the following.

• Is susceptible to measles (not immune)
• Has a classical measles presentation.
• Has been in an area with known measles cases during the incubation period. 

Under investigation: A person who has been notified to the medical officer of health, but information is not yet available to classify it further.

Not a case: A person who has been investigated and subsequently found not to meet the case definition.

A clinically compatible illness is characterised by all of the following.

• Cough and/or coryza and/or conjunctivitis and/or Koplik’s spots present at the time of rash onset.
• Fever (at least 38ºC if measured) present at the time of rash onset.
• Generalised maculopapular rash, starting on the head and neck then spreading downwards and outwards and fading.

Note: Some people may present with an illness that does not meet all the above criteria (e.g. if they have had previous vaccination or infection). These cases require laboratory definitive evidence to be classified as a confirmed case.

An epidemiological link is established when there is contact between two people with a plausible mode of transmission at a time when one of them is likely to be infectious and the other has onset of illness within the incubation period.

Laboratory definitive evidence

Detection of measles virus by polymerase chain reaction testing. If vaccine strain measles is suspected, this must be excluded (refer to laboratory testing guidelines).

Laboratory suggestive evidence

Confirmation of IgG seroconversion between paired sera tested in parallel or IgM detection in an unvaccinated person.

Refer to Appendix 4: Direct laboratory notification of communicable diseases flowcharts – Health New Zealand | Te Whatu Ora for the direct laboratory notification process for measles.

• To confirm or exclude a diagnosis of measles in a suspected case (measles PCR)
• To exclude vaccine strain virus in a confirmed case who has recently been vaccinated (vaccine strain-specific PCR or genotyping)
• To determine measles immune status in a contact (serology IgG)
• To track transmission pathways during a measles outbreak (Genotyping via Sanger Sequencing or whole genome sequencing)

Health practitioners should promptly notify the local medical officer of health of suspected cases. The medical officer of health should ensure that polymerase chain reaction (PCR) tests for individuals from communities likely to be most severely impacted by a measles outbreak (refer to Priority groups for public health action) get to the processing lab as soon as possible.

The medical officer of health or other public health service clinical staff should discuss urgent cases with the on-call clinical microbiologist, so laboratory staff are aware of the urgency and can prioritise the sample for prompt processing. The clinical microbiologist is the point of contact with the laboratory.

A sample that requires urgent processing should be marked ‘Urgent Public Health’.

Polymerase chain reaction (PCR) testing is the primary diagnostic tool. Laboratory confirmation requires a PCR positive result for measles. Refer to Laboratory criteria (laboratory definitive evidence and laboratory suggestive evidence) for confirmed and probable case interpretations.

1. Measles polymerase chain reaction (PCR) (nucleic acid amplification test)

Measles PCR on a nasopharyngeal sample is the preferred test. Measles virus is detectable from 3 days before rash onset (rash onset is day 0) to 7 days after rash onset. The routine measles PCR test does not distinguish between wild type and vaccine strain. This is done by vaccine-strain-specific PCR. 

PCR tests have the highest diagnostic sensitivity when samples are collected at first assessment of a suspected case (maximum sensitivity is within 3 days of rash onset, but reasonable sensitivity is observed up to 7 days after rash onset).

Nasopharyngeal or oropharyngeal samples have the highest yield particularly in the 7 days after rash onset. Urine testing can be useful for those presenting after this time but should not be used in place of a nasopharyngeal or oropharyngeal swab. Discussion with a clinical microbiologist is advised if testing more than 7 days after rash onset.

All requests for measles PCR, and samples referred for genotyping or testing for the presence of the measles vaccine strain should have recent vaccination status included on the referral form.

2. Serology

Serology is primarily used to determine the immunity status of contacts. However, it can be used for diagnostic purposes where it could be considered laboratory suggestive evidence for confirmed measles infection.

The request form must state which investigation is required, immune status (IgG) or query infection (IgG and IgM). Full clinical details, including date of rash onset, will ensure the correct tests are performed. Refer to Samples and timings for sample requirements.

Serology (Immunoglobulin IgM and IgG paired testing) to determine acute infection

Note: Paired IgM and IgG paired serology is not generally recommended for diagnosis of measles. 

The use of serology in the investigation of a suspected measles case is only recommended where PCR testing is not possible AND it is requested by a medical officer of health after discussion with a clinical microbiologist.

IgM and IgG paired serology for an acute infection is often unreliable, particularly in previously vaccinated people or due to cross-reactions from other viral infections.

Recent vaccination can result in an IgM response, and previously vaccinated but infected people may not develop an IgM response. IgM serology confirmed by the laboratory may occasionally help with diagnosis in late presentations. Any positive IgM result should be discussed with a clinical microbiologist.

Serology will not distinguish between wild type and vaccine strain measles.

Measles IgG detected without IgM within 1 to 2 days of a rash onset strongly suggests prior immunity and that the rash is more likely due to causes other than measles. The IgG results also offer limited value to inform public health actions given the second sample is required 2 weeks after the initial blood serology test.

Serology (Immunoglobulin G IgG) to determine immune status 

Serology is most useful for confirming immunity in people whose vaccination history is uncertain, although commercial tests do not detect all vaccine-induced immunity. Refer to Contact management for guidance on when to do serology testing in contacts.

Vaccine strain-specific genotyping

Vaccine strain-specific PCR is used to determine if a positive measles PCR result is due to recent vaccination. This is done by amplifying a specific part of the measles virus (RNA sequence) that is only present in the vaccine strain. If this sequence is identified via vaccine strain-specific PCR, vaccine strain measles is confirmed. 

Vaccine strain-specific PCR is reflex tested by diagnostic laboratories on cases with a positive measles PCR that do not have travel history and/or no contact or epi-link to a confirmed case but have a history of recent vaccination. For all other measles PCR positive cases vaccine strain-specific PCR should only be requested after discussion between the medical officer of health and the clinical microbiologist.

Occasionally, a vaccinated person with no known exposure to the measles virus can return a positive vaccine strain-specific PCR result many months after vaccination due to vaccine strain fragments still being detectable. Any positive vaccine strain-specific genotyping result that occurs more than 90 days after vaccination requires a discussion between the medical officer of health and clinical microbiologist to ensure the individual is managed appropriately.  The presence of vaccine strain measles does not rule out potential co-infection with the wild-type strain, as both strains of the measles virus can be present at the same time. Generally, this is seen when a person is vaccinated as part of a vaccination campaign surrounding a measles wild type outbreak and has not had the ability to produce enough antibody response to prevent becoming infected with the wild type of measles virus. If there is a suspicion of co-infection, the sample can be tested at the National Measles and Rubella Reference Laboratory (NMRL) at Canterbury Health Laboratories for the presence of both vaccine and wild type strains. A discussion with the clinical microbiologist will determine if additional testing beyond confirmation of vaccine strain is necessary.

3. Whole genome sequencing

Genotyping via Sanger Sequencing or whole genome sequencing (performed at the NMRL), is used for epidemiology and outbreak investigation.  It allows genetic characterisation of the virus on measles positive PCR samples.

Genotyping via Sanger sequencing is conducted on measles positive PCR samples:

• new importations
• index cases and the first 5 to 10 cases of an outbreak/cluster. If the outbreak continues, then a strategy for ongoing sequencing of the outbreak should be developed.
• sporadic cases that are not epidemiologically linked to other genotyped cases or clusters
• samples requested by the medical officer of health investigating the outbreak

Whole genome sequencing is conducted on positive measles PCR requested by the medical officer of health investigating the outbreak to further determine if cases are epidemiologically linked.

All suspected cases of measles must be immediately notified to the local public health service by attending health practitioners and should not wait for laboratory confirmation. Notification forms can be found on regional Community Health Pathways (external link).

Urgent notification by phone is recommended where there is a high index of suspicion for measles.

Healthcare practitioners should have a high index of suspicion for measles in individuals who have a clinically compatible illness and are either a contact of a confirmed or probable measles case or meet all of the following criteria.

• Recent overseas travel or attendance at a measles location of interest
• Non-immune, partially vaccinated or unknown vaccination history.

Public health services should ensure complete case information is entered into the appropriate surveillance database for notifiable diseases (i.e. NDMS).

National escalation is:

• required for all confirmed and probable cases
• recommended for suspected cases where there is a high index of suspicion for measles, at the discretion of the medical officer of health
• not required for other suspected cases
• required for national coordination when cases, contacts, exposure events or outbreaks cross regional boundaries.

Refer to Appendix 5: Escalation Pathways for more information.

Reporting to the World Health Organization

The Ministry of Health’s International Health Regulations National Focal Point must notify the World Health Organization (WHO) of events involving measles due to the possibility it could   constitute a public health emergency of international concern. The National Focal Point must also use the International Health Regulations Decision Instrument (refer to Annex 2 of the International Health Regulations (external link) [PDF]) for any unusual or potentially serious public health event and then notify WHO if required.

The National Focal Point will notify the WHO as soon as possible and no later than 72 hours after receiving notification of the measles case.

National Focal Point notifications

A national focal point notification should be considered when a measles case or close contact identified in Aotearoa New Zealand may pose a public health risk to another country. Examples include when:

• the source of the case’s infection is likely to be another country
• the case was infectious while in another country
• close contacts of the case have travelled to another country.

National Focal Point notification requests should be sent to protection.clinical@tewhatuora.govt.nz and NISoperations@tewhatuora.govt.nz.

Measles is a high-priority disease requiring an urgent public health response to prevent and contain transmission. Case investigation should occur the same day as notification for all confirmed and probable cases. Limited case investigation, including identification of high-risk exposure events, may be undertaken for suspected cases where there is a high index of suspicion for measles at the discretion of the medical officer of health.

A manaaki-centred approach to case follow-up is crucial for establishing relationships and trust between public health services, cases and their contacts. For more information on this approach refer to the Equity and Te Tiriti o Waitangi and Māori Health chapters.

Measles is highly infectious and requires a period of isolation. Most people feel very unwell and it can be a distressing time for the case and their whānau. The following approaches should be prioritised when engaging with cases and their whānau.

• Carefully balance the need to act quickly to prevent and contain a measles outbreak with taking some time to build trust and meaningfully connect with the case and their whānau.
• Check cases can continue to isolate safely and successfully. Any concerns that might impact the case’s ability to isolate safely should be identified and support provided where possible (refer to Appendix 7: Manaaki and Welfare).
• Frame the conversation around what matters to the case and their whānau, considering what implications public health actions will have on their day-to-day life. For example, they may be a sole caregiver who will need to make alternative arrangements if isolating or they may live in a multi-generational home where isolation from others will be difficult. Walk through their options considering the impact of the public health action required.
• Ensure access to appropriate and understandable information about measles through the use of interpreters and translated information as needed.

For further information about support that is available refer to Appendix 7: Manaaki and Welfare.

Case investigation should focus on:

• confirming the diagnosis of measles
• calculating the infectious period of the case
• identifying cases at higher risk of severe illness
• determining the likely source of infection (source investigation)
• identifying close contacts and exposure events
• determining if support is required for safe isolation.

Confirming the diagnosis 

The case’s symptoms, measles vaccination history and test results should be reviewed to determine if the case meets the case definition for measles (refer to case definition). The possibility of vaccine associated measles, or co-infection with wild strain and vaccine strain measles should be considered and excluded where appropriate. This may require discussion with the clinical microbiologist (refer to the laboratory testing guidance for further details).

• Clinical presentation: a detailed symptom history should be undertaken to confirm the symptoms are consistent with measles.
• Measles vaccination history: the date and age at time of vaccination should be obtained. If MMR vaccination occurred within the previous 90 days, the potential for symptoms to be due to recent vaccination or vaccine-associated measles should be considered.
• Test results: public health services should ensure the appropriate test (i.e. polymerase chain reaction test) was performed and where appropriate should confirm that vaccine strain virus has not been detected (refer to the laboratory testing guidance for further details).  

Calculating the infectious period of the case

The date of rash onset is used to calculate the infectious period. The infectious period lasts from 4 days before rash onset until 4 days after rash onset with rash onset date considered day 0 (Figure 2).

Identifying cases at higher risk of severe illness

Cases at higher risk of severe illness should be identified to facilitate early referral to the appropriate clinical team (e.g. infectious disease, obstetric, paediatric) if required.

Determining the likely source infection (source investigation)

Intensive source investigation is required during the ‘stamp it out’ phase (refer to the Outbreak control section and the measles toolkit (external link)). Public health services should focus on the 7 to 14 days prior to rash onset with extension to 21 days if no source is identified. 

Cases should be asked about: 

• contact with a confirmed or suspected measles case (including anyone with measles-like symptoms even if measles was not confirmed)
• recent travel or close contact with someone who has a history of recent travel to areas where measles is circulating.

Identifying close contacts and exposure events

A detailed chronological history should be taken of the case’s movements on each day of their infectious period, to identify:

• people they had contact with
• people who live with the case or visited the household
• workplace exposures. The case should be asked about work in settings with a high risk of transmission or individuals at higher risk of severe illness (e.g. healthcare, schools/early childhood education)
• all healthcare facilities they attended. Case should be asked about mask use, and whether they were isolated on arrival
• all other settings visited by the case. The case should be asked about attendance at any settings with a high risk of transmission including early childhood education centres, schools, workplaces, transport, flights, large events.

Refer to the Exposure Event Management section for details.

Determining if support is needed for isolation

Public health service staff should discuss with the case and/or whānau any concerns that might impact the case’s wellbeing or their ability to isolate safely so that support can be provided to address these concerns where possible (refer to Appendix 7: Manaaki and Welfare).

Isolation

Suspected cases awaiting test results should be advised to isolate until measles has been excluded. 

Community cases

Confirmed and probable cases being cared for in the community must isolate until they have completed 4 full days of isolation after rash onset, with the day of rash onset counted as day 0.  

Hospitalised cases

Suspected, probable and confirmed cases presenting to healthcare settings should be put in airborne precautions (in a negative pressure room). If a negative pressure room is not available, discuss risk assessment and room prioritisation with the infection prevention and control team.

The case should wear a N95/P2 mask when being transported within the hospital. For immunocompromised cases (including cases who are pregnant or with with severe ventilated pneumonitis), airborne precautions may need to be maintained for longer than the usual isolation period for cases (i.e. longer than 4 days after rash onset) and potentially for the duration of their illness.  

Only healthcare workers, cleaners and support staff who have documented immunity to measles should enter an airborne isolation room. 

Release from isolation

Community cases

All cases in the community can be released from isolation on day 5 even if they have ongoing symptoms.   

Cases with symptoms at the end of their isolation period should be advised to stay home and recover until they feel well enough to return to normal activities.

Hospitalised cases

Release from isolation will be managed by the appropriate clinical team. A minimum isolation period of 4 days after rash onset is required. However, airborne precautions may need to continue for cases who are immunosuppressed and those who have very severe illness.

Community cases

All cases should be advised of the signs of clinical deterioration and advised to seek urgent medical advice if these occur.

Public health services should monitor community cases for the duration of their isolation period. The daily follow up should include the following.

• Checking they can continue to isolate safely and successfully. Any concerns that might impact the case’s ability to isolate safely should be identified and support provided where possible (refer to Appendix 7: Manaaki and Welfare).
• A daily symptom check. The public health service should facilitate urgent clinical review if there is evidence of deterioration. 
• Checking overall wellbeing.

Public health services should have a low threshold for facilitating early clinical review for cases at higher risk of severe illness including Māori and Pacific cases and those from socioeconomically deprived communities. These groups were observed to experience higher rates of hospitalisation during the 2019/2020 measles outbreak.

Hospitalised cases

Public health services are not required to monitor hospitalised cases. However, public health services may follow up with the hospital to confirm outcomes such as date of discharge, for completing NDMS records.

There is no antiviral therapy available for measles. Supportive care should be provided. 

Vitamin A treatment may be considered in hospitalised infants and children as per the Starship measles clinical guideline (external link). This will be guided by the relevant hospital team (e.g. paediatrics, infectious diseases).

Cases and/or their caregivers should be provided with clear information about measles, what isolation means what they need to do to keep themselves and their whānau safe and how to prevent transmission of measles to others. This includes:

• staying home except to access urgent healthcare
• avoiding all contact where possible, with anyone they live with who is not immune to measles especially if anyone they live with is at higher risk of severe illness. This also includes not spending time in shared spaces, even when the shared space is not occupied by others (as the virus can stay in the air for up to 2 hours).
• wearing a medical or N95/P2 mask and opening windows (where possible) when spending time with anyone who is not immune to measles
• not having visitors to the house.

They should also be advised of the signs of clinical deterioration and what to do if these develop.

If a case needs to visit a healthcare facility, the case and/or their caregivers should be advised to phone ahead so the facility can safely isolate the case on arrival. The case should be advised to wear a medical or N95/P2 mask (an N95/P2 mask will contain more droplets than a medical mask but may not be tolerated by the wearer) to reduce the risk of infecting others.

At release from isolation, all cases should be provided with the following advice on:

• accessing clinical care if they have ongoing symptoms
• potential prolonged immunosuppression post recovery and the importance of early clinical review if they develop symptoms of an infectious illness
• measles, mumps and rubella (MMR) vaccination to protect against mumps and rubella as the case’s susceptibility to measles means they are likely not immune to the other two diseases in the MMR vaccine.

Cases who were not confirmed by PCR testing (i.e. cases with clinically compatible measles illness and epidemiological link to a confirmed case), should discuss with their doctor whether having serology testing to confirm their immunity to measles would be worthwhile. This would provide reassurance that they are protected and would also mean they will not have to quarantine in the future if identified as a close contact. Completing a full 2 vaccine MMR schedule to protect from mumps and rubella would also provide this assurance.

An information sheet and case letters, including translated and accessible formats, are available here (external link) and public facing information is available here Measles – Health and information services (external link).

The primary goal of contact tracing for measles is to prevent onward transmission. Contact tracing should be initiated as soon as possible. An urgent response is required because one case of measles can lead to a large outbreak. In a non-immune population one measles case could result in another 12 to 18 cases within 10 to 14 days. Refer to spread of infection for more information.

Where prioritisation is required, public health services should prioritise follow up of contacts at settings with the highest risk of transmission and contacts with the earliest quarantine date.

Manaaki and wellbeing considerations are the same for cases and contacts.

Refer to the Manaakitanga/Manaaki in practice for guidance.

Measles contacts are defined by the extent of their exposure to a case and subcategorised by their immunity status. Contacts can also be defined by their risk of developing severe disease. 

Note: 

• Contact categorisation will not change in contacts who receive post-exposure immunoglobulin prophylaxis.
• Contacts who are immunosuppressed may still be susceptible to measles even if they are fully vaccinated or have had a previous measles infection. Refer here (external link) for more guidance. 

Classification of contacts by level of exposure 

1. Close contact 

A close contact is anyone who had any of the following exposures to a case during their infectious period. 

• Face-to-face contact of any duration. 
• Spent time (of any duration) in a confined indoor space at the same time as the case. 
• Spent time (of any duration) in a confined indoor space within 1 hour^a of the case leaving the space.

^aAlthough the measles virus can remain viable for up to 2 hours a pragmatic recommendation of 1 hour was made by the Clinical and Technical Advisory Group involved in development of the measles chapter.

A medical officer of health may use their discretion to apply a shorter or longer time for contact tracing purposes. For example, in a healthcare setting a shorter stand down period of 35 minutes is likely to be appropriate in airborne infection isolation rooms (AIIR) depending on the number of air changes per hour, refer to CDC guidance (external link). Refer here (external link) for more guidance. A 2-hour period may be appropriate for exposures in very small and poorly ventilated spaces because the measles virus can survive for up to 2 hours in the air.

Mask use by the case and/or contact may reduce the risk of a contact becoming infected with measles, however evidence for this is not established. In healthcare settings, staff members who use appropriate personal protective equipment, including an N95/P2 mask, will not be considered close contacts.

Confined indoor spaces may include, but are not limited to, any of the following: classrooms, houses, healthcare settings (including inpatient rooms, waiting rooms, consultations rooms), workplaces and transport services (cars, buses, trains and domestic and international flights). 

Unidentifiable contacts who meet the close contact definition may be informed of their exposure through general communications (e.g. locations of interest, social media, newsletter) and subsequently self-identify via Healthline or primary care.

Examples of unidentifiable close contacts are:

• individuals travelling on a bus where contact details are not available
• attendees of a small indoor event where there is no register of attendees.

2. Casual contact 

Casual contacts are individuals who have been in a setting or at an event attended by an infectious measles case, where the level of exposure is either unlikely to meet the close contact definition or cannot be determined but there is possibility of transmission. Casual contacts may or may not be individually identifiable.

The casual contact category should not be used just because contacts cannot be identified. Unidentifiable contacts who meet the close contact definition should be defined accordingly and receive appropriate public health management if they self-identify.

If a risk assessment determines that all contacts at a setting have had sufficient exposure to put them at high risk of developing measles (e.g. they travelled in a bus with an infectious case), they should be deemed close contacts.

They are considered a casual contact if any of the following apply.

• An infectious case attended a large event such as a sports stadium, where it is not possible to do an individual risk assessment to determine each contact’s level of exposure. For the attendees to be classified as casual contacts a medical officer of health must be satisfied that at least some of the individuals who attended the event could have had sufficient contact with the infectious measles case to put them at risk of infection. 
• An infectious case was present in a clearly defined area of a setting such as a school. The casual contact designation can be used for other individuals in that setting if a medical officer of health determines it is likely that other individuals at that setting (e.g. the wider school campus) had contact with the infectious case (e.g. passing them in a corridor). This categorisation applies where the level of exposure outside the classroom setting cannot be determined, and any contacts are unable to be identified.

Examples of casual contacts are:

• attendees of a large event where it is not possible to identify individual contacts or ascertain their level of exposure, however, the medical officer of health has determined that there is a possibility of transmission
• school students and staff who have been in the school cafeteria where it is not possible to identify individual contacts but there is a possibility of transmission.

Classification of contacts by immune status 

1. Immune  

A contact will be classified as immune if any of the following apply. 

• They were born or living in Aotearoa New Zealand before 1 January 1969. This is because prior to the measles vaccine being introduced to Aotearoa New Zealand in 1969, most people would have been exposed to measles and have developed immunity. A medical officer of health has discretion to apply a different date cut off for contacts born outside of Aotearoa New Zealand as measles vaccine was introduced earlier in some countries (e.g. USA 1963). These contacts may require evidence of immunity.
• They have received 2 doses of a measles-containing vaccine (e.g. MMR), given at least 4 weeks apart and both were given after their first birthday.
• They received their second MMR within 72 hours of first exposure to an infectious case. 
• They have serology results confirming they are immune.
• They have evidence of a previous measles infection confirmed through testing (e.g. PCR result).

2. Susceptible – partially vaccinated

A contact is classified as susceptible – partially vaccinated if they have had a single measles-containing vaccine which was administered after the age of 12 months and at least 4 weeks prior to their exposure to a measles case. This includes infants aged between 12 and 15 months who are age appropriately immunised with one dose of MMR.

Close contacts who received a single measles containing vaccine who undergo serology testing should be categorised as either immune or susceptible – non-immune, according to the results.

• Priorix - Immunisation Advisory Centre (external link)
• Measles | Red Book: 2024–2027 Report of the Committee on Infectious Diseases | Red Book Online | American Academy of Pediatrics (external link)

3. Susceptible – non-immune  

A contact is classified as susceptible – non-immune if they do not meet the criteria for any other category.

This includes the following individuals. 

• Contacts who have not previously received any measles containing vaccine (MMR). 
• Contacts who have received one MMR vaccine, but it was administered prior to 12 months of age (MMR0) or less than 4 weeks prior to their exposure to a case. 
• Contacts with serology results indicating they are not immune (this also applies even if the result is equivocal [36] or they have evidence of previous infection or vaccination). 
• Contacts who received their MMR1 as post-exposure prophylaxis (this applies to the current exposure only).

Impact of immunosuppression on immunity to measles  

If a contact is immunosuppressed, they may require further assessment to determine their immune status as they may be susceptible to measles even if they have evidence of prior immunity.

Therefore, all immunosuppressed contacts should undergo a rapid assessment to determine their eligibility for post-exposure immunoglobulin prophylaxis. Casual contacts are not routinely assessed for immunosuppression and post-exposure prophylaxis (PEP) is not administered to them. Immunosuppressed or immunocompromised contacts may include:

• individuals receiving chemotherapy, radiotherapy, high dose steroids, immune modulating/immunosuppressive drugs, or biological therapies (e.g. monoclonal antibodies)
• individuals with HIV, AIDS, or cancer
• individuals who have received an organ transplant, or a bone marrow transplant
• renal patients on dialysis and people with primary immunodeficiencies [26,37,38] refer to the Starship guidance (external link) or the UK Guidance on measles (external link) for more information. 

Discussion with the contact’s clinical team is required. 

Classifying contacts at higher risk of severe illness 

Contacts at high risk of becoming very unwell with measles include those who are:

• infants aged under 12 months
• immunocompromised
• pregnant or up to 6 weeks post-partum and not immune
• children aged under 5 years and not immune.

These contacts may be eligible for post-exposure immunoglobulin prophylaxis (refer to prophylaxis).

Contact investigation should focus on determining the following.

• The extent of the contact's exposure to the case (refer to Close contact and Casual contact).
• The immune status of the contact.
• The quarantine (or restriction) period for the contact.
• Whether the contact is at higher risk of severe illness and should be considered for post exposure MMR or immunoglobulin prophylaxis.
• The feasibility of post exposure MMR prophylaxis.
• Whether a contact would have difficulties quarantining (refer to Serology testing of contacts below).

Assessing contact immunity 

The immune status of a close contact determines whether they are subcategorised as: 

• immune  
• susceptible – partially vaccinated
• susceptible – non-immune. 

In all circumstances, evidence of immune status is required. This means that contacts should be managed as susceptible - non-immune until evidence of immunity is provided. 

Serology testing of contacts 

During the ‘stamp it out’ phase of an outbreak, serology (IgG) testing should be used to determine immunity in close contacts if either their vaccination status is unknown, or they are partially vaccinated and understanding their immune status is required.  This ensures that people who are immune can avoid unnecessary quarantine or restrictions.

Where there is limited serology testing capacity, prioritisation of individuals for serology testing should be done in partnership with equity advisors.

When prioritising serology these groups should be considered when making decisions.

• Individuals at higher risk of severe illness, for whom post-exposure immunoglobulin prophylaxis may be recommended (noting this needs to be within 6 days of exposure).
• Contacts who would find quarantining difficult for financial, social, and/or mental health reasons. This aspect should always be considered for Māori, Pacific and socioeconomically deprived peoples.
• Healthcare workers, and other workers performing critical functions, particularly if the service may not be able to continue to operate due to insufficient staff, for example, teachers.
• Individuals who have received a single MMR vaccine and would otherwise be restricted from attending high risk settings.
• Contacts who report being vaccinated in Aotearoa New Zealand or overseas and are unable to provide adequate evidence of vaccination.

Close contacts with serology that is negative or equivocal will be managed as susceptible – non-immune (serology supersedes evidence of vaccination).

For this reason, partially vaccinated contacts should be advised of this before offering serology testing to exempt a contact from restriction requirements.

Monitoring and testing of symptomatic contacts 

All contacts (including casual contacts and immune contacts) should be advised to self-monitor for symptoms of measles for a total of 21 days from their last exposure to an infectious case even if they are not in quarantine (this is based on the full incubation period for measles). Contacts who receive post-exposure immunoglobulin prophylaxis should be advised to self-monitor for a total of 25 days from their last exposure (this is because immunoglobulin may extend the incubation period). If symptoms develop, they should be advised to stay home and contact public health, Healthline or their primary care provider for further advice. 

Casual contacts and immune close contacts 

• No active monitoring by public health services is required. 
• Advice to casual contacts may be provided as part of exposure event management or through public communications such as the locations of interest website or media statements.

Susceptible – partially vaccinated close contacts 

• Public health services should consider monitoring partially vaccinated close contacts for signs and symptoms consistent with measles for the duration of their restriction period. Monitoring frequency is expected to be less than for susceptible - non-immune contacts (see next section). 
• If a contact develops symptoms of measles they should be advised to stay home until measles is excluded. If testing is required, this should occur once the rash has developed, unless there are compelling reasons to do it earlier.
• A second dose of MMR should be offered as soon as possible after the period of restriction has ended. This second dose should be administered at least 4 weeks after the first dose. 

Susceptible – non-immune close contacts 

Public health services should actively monitor susceptible – non-immune contacts for the duration of their quarantine period.

Contacts with symptoms at the end of their quarantine period should be advised to stay home and monitoring should continue until measles has been excluded.

If testing is required, this should occur once the rash has developed, unless there are compelling reasons to do it earlier, in discussion with a clinical microbiologist.

All contacts (including casual contacts and immune contacts) should be advised to self-monitor for symptoms of measles for a total of 21 days from their last exposure to an infectious case even if they are not in quarantine (this is based on the full incubation period for measles). Contacts who receive post-exposure immunoglobulin prophylaxis should be advised to self-monitor for a total of 25 days from their last exposure (this is because immunoglobulin may extend the incubation period). If symptoms develop, they should be advised to stay home and contact the local public health service, Healthline or their primary care provider for further advice.

Casual contacts and immune close contacts 

• No active monitoring by public health services is required. 
• Advice to casual contacts may be provided as part of exposure event management or through public communications such as the locations of interest website or media statements.

Susceptible – partially vaccinated close contacts 

• Public health services should consider monitoring partially vaccinated close contacts for signs and symptoms consistent with measles for the duration of their restriction period. Monitoring frequency is expected to be less than for susceptible – non-immune contacts (refer to susceptible – non-immune close contact). 
• If a contact develops symptoms of measles they should be advised to stay home until measles is excluded. If testing is required, this should occur once the rash has developed, unless there are compelling reasons to do it earlier, in discussion with a clinical microbiologist.
• A second dose of MMR should be offered as soon as possible after the period of restriction has ended. This second dose should be administered at least 4 weeks after the first dose. 

Susceptible – non-immune close contacts 

Public health services should actively monitor susceptible – non-immune contacts for the duration of their quarantine period.

Contacts with symptoms at the end of their quarantine period should be advised to stay home and monitoring should continue until measles has been excluded.

If testing is required, this should occur once the rash has developed, unless there are compelling reasons to do it earlier, in discussion with a clinical microbiologist.

Management of contacts differs according to their level of exposure to a case (close or casual contact) and their immune status. 

Casual contacts and immune close contacts 

No quarantine or restrictions are required.

Susceptible – partially vaccinated close contacts  

In the absence of serology testing, it is not possible to determine the immune status of partially vaccinated contacts. Up to 10% of people vaccinated with one dose of the MMR vaccine will have no immunity to measles and are therefore at high risk of infection and transmission to others [39,40,41]. For more information refer to the Immunisation Handbook.

From 7 days after their first exposure until 14 days after their last exposure, these contacts should be excluded from attending settings where there is a high risk of transmission and should be advised to avoid contact with individuals at higher risk of severe illness. This calculator (external link) can be used to define the restriction period. The following restrictions are recommended.

• Exclude from high-risk settings where close contact occurs (e.g. schools or early childhood education centres), where there is a high risk of transmission of measles. 
• Exclude from visiting settings where there could be people who are at higher risk of severe illness (e.g. hospitals, vaccination centres and other healthcare settings). People working in these settings should be excluded for 21 days (see below).
• Avoid contact, where possible, with people who are at higher risk of severe illness. For example, infants under 12 months, people who are immunosuppressed; or pregnant or up to 6 weeks post-partum (unless you know they are fully vaccinated prior to pregnancy). Exclude from international travel, particularly to regions or countries with low MMR vaccination rates.

Partially vaccinated close contacts who require health care should be advised to phone ahead and say they are a measles close contact to enable appropriate infection prevention and control measures. The contact should be advised to wear a medical or N95/P2 mask.

A medical officer of health may recommend additional restrictions following a risk assessment.

Hospitalised partially vaccinated close contacts

Hospitalised partially vaccinated close contacts should have serology testing to confirm their immune status. If serology testing is not done, they should be placed in airborne precautions (i.e. in a negative pressure room) for the full 21-day incubation period. If a negative pressure room is not available, discuss risk assessment and room prioritisation with the infection prevention and control team.

If released from hospital during the restriction period, the public health service will take over management and monitoring and should call the person to remind them about the restriction requirements.

Healthcare workers

Healthcare workers who are partially vaccinated should have serology testing to confirm their immune status and should be managed according to the results. If serology testing is not performed, they should be excluded from working in a healthcare facility from day 7 after their first exposure until 21 days after their last exposure to an infectious case, due to the ongoing risk of developing measles and the vulnerability of patients in healthcare settings.  Healthcare workers should discuss their work options with the occupational health team. Occupational health may recommend that the exclusion period start as early as 5 days after first exposure to the case [40].

Susceptible non-immune close contacts  

These contacts should quarantine (i.e. stay home unless seeking necessary health care) from 7 days after their first exposure to an infectious case until 14 full days after their last exposure. This means quarantine will be for a minimum of 8 days.

If exposure extends over multiple days or involves exposure to several cases with different infectious periods, the quarantine period will be extended until 14 full days after their last exposure. Quarantine may also be extended (or additional restrictions recommended) if the contact is symptomatic at the end of the quarantine period and is being investigated as a possible case. 

Contacts who have received post-exposure immunoglobulin prophylaxis will have their quarantine period extended to 18 days (i.e. from 7 days after their first exposure to an infectious case until day 18 from their last exposure).

This calculator (external link) can be used to define the quarantine period. 

Hospitalised non-immune close contacts

While hospitalised, non-immune close contacts should be placed in airborne precautions (i.e.  a negative pressure room) for the full 21-day incubation period. If a negative pressure room is not available, discuss risk assessment and room prioritisation with the infection prevention and control team.

If released from hospital during the quarantine period, the public health service will take over management and monitoring. The quarantine period will be from 7 days after their first exposure to an infectious case, until day 14 from their last exposure.

Healthcare workers 

Healthcare workers who are confirmed to be non-immune are required to quarantine. After completing quarantine, they should be excluded from working in a healthcare facility until 21 days after their last exposure to the infectious case, due to the ongoing risk of developing measles and the vulnerability of patients in healthcare settings. Healthcare workers should discuss work options with their occupational health team. Occupational health may recommend that the exclusion period start as early as 5 days after first exposure to the case.

Immunoglobulin post-exposure prophylaxis 

Immunoglobulin post-exposure prophylaxis (PEP) should be considered for close contacts who meet the eligibility criteria (see below).

Immunoglobulin PEP can reduce the severity of illness but will not prevent, measles.

Immunoglobulin PEP must be given as soon as possible after the close contact was initially exposed to a measles case and can be given up to a maximum of 6 days after the initial exposure. There is no benefit to giving immunoglobulin PEP if the close contact is already exhibiting symptoms of measles (including prodromal symptoms).

Assessing eligibility

All close contacts should be assessed to see if they meet the eligibility criteria. Māori and Pacific Peoples must be prioritised for urgent assessment due to strong credible evidence from the 2019/2020 measles outbreak that showed Māori, and Pacific Peoples were substantially more likely than non-Māori, non-Pacific to be hospitalised [4].

To assist with determining eligibility, the immune status for close contacts should be determined as soon as possible; this may require serology testing. If a serology result is not available rapidly, administration of immunoglobulin PEP should not be delayed if approaching or at day 6 following initial exposure.

The final decision on immunoglobulin PEP administration should be made with the relevant hospital clinician.

Eligibility criteria

Immunoglobulin PEP is recommended for the following groups who are at higher risk of severe illness requiring hospitalisation. Where prioritisation is required, close contacts should be offered immunoglobulin PEP in this order.

1. Immune compromised or immune-deficient people [see the UK National measles guidelines July 2024 (external link)].
2. Non-immune (susceptible) and pregnant^a including up to 6-weeks post-partum.
3. Infants under 6 months subject to assessment of maternal immune status^b. 
4. Infants aged 6 to 12 months who cannot receive post-exposure MMR0 (if it is more than 72 hours since the initial exposure).  
5. Other groups may be considered at the discretion of the medical officer of health.

^a If exposure occurs during pregnancy and measles immune status is unknown discuss urgent serology testing with the laboratory. Note: a measles IgG test can be requested as an add-on to antenatal sera samples taken within the last 12 months.

^b Maternal protection wanes through the first 6 months of an infant’s life; evidence of vaccination status or maternal serology tests may not predict protection for young infants (particularly from 3 months). The medical officer of health should seek advice from a paediatric clinician when determining immunity in infants under 6 months. Infants born prematurely before 28 weeks’ gestation are considered non-immune irrespective of maternal immune status.

Accessing immunoglobulin

There is national variation for how measles immunoglobulin PEP is accessed. Public health services may liaise directly with the relevant hospital clinician or contact their local blood bank directly, or in accordance with their local processes to discuss a close contact’s eligibility and request immunoglobulin.

Immunoglobulin is obtained from a blood bank through a prescription from the public health service or the administering hospital or clinical service.

The New Zealand Blood Service operates a 24-hour on-call service for medical advice. The local hospital blood bank can provide details for the New Zealand Blood Service on-call medical officer.

A list of all the public health services and their process for accessing immunoglobulin is available here (external link).

Dose

The New Zealand Blood Service has advised that the level of measles-specific antibody in normal immunoglobulin is lower than recommended, due to lower antibody levels in donors. The recommended doses (external link) of normal immunoglobulin are:

Contacts should monitor for symptoms for 21 days after their last exposure to the case as this is the full incubation period for measles. If symptoms develop, they should remain at home and contact the local public health service or their healthcare provider.

Contacts who receive post-exposure immunoglobulin prophylaxis should monitor for symptoms for 25 days from their last exposure, as immunoglobulin may extend the incubation period.

Contacts who require health care should be advised to phone ahead and inform health care facility staff they are a measles close 

Contacts should be encouraged to get vaccinated as soon as possible after completing their period of quarantine or restriction.

The primary goal of exposure event management is to prevent and control transmission of measles within a setting and prevent spread into the community.  

Exposure event management involves:

• rapid identification of exposure settings
• assessing risk and determining prioritisation of public health follow-up
• setting management
  • liaison and ongoing guidance and support
  • identification and management of close contacts
  • support with communication
• implementing other control measures such as publishing a location of interest and considering ring vaccination. 

An exposure event is defined as any place or setting a case attended during their infectious period where other people were present.

Exposure events are identified during case investigation. Additional information about an exposure event may come from other sources including caregivers, manager, leader or other staff and other attendees.

Risk assessment of an exposure event is undertaken to:

• classify contacts as close and/or casual (refer to contact management)
• guide the contact management plan
• determine the urgency of public health follow up.

The risk assessment should consider the following risk components.

1. Transmission within the setting.
2. Wider community spread.
3. Presence of contacts at higher risk of severe illness.

The risk assessment should also consider prioritisation of public health service follow-up.

The tables below outline the components of risk assessment that guide decision-making for classifying contacts and prioritisation of management of the exposure event.  

The risk assessment and management plan should be documented in NDMS for consistency of attendee follow up and should be updated as new information, particularly immune status of attendees, becomes available.

Where the medical officer of health considers the exposure event to be of higher risk, this should be highlighted as a ‘red flag’ in NDMS. Examples of ‘red flags’ are provided for each component of risk assessment.

Setting management

Appropriate engagement with setting staff, and provision of ongoing support, is key to effective management of an exposure event.

The public health service should identify the key contact person at the setting (e.g. the manager) as soon as possible. When interacting with hāpori (community) Māori settings such as marae/kohanga, public health services should work alongside Māori leadership from within the setting for joint decision-making and guidance. When interacting with Pacific settings such as Pacific churches, public health services should work alongside Pacific leadership. 

Public health service actions should include the following as required.

• Introduce self and role of the public health service.
• Inform the manager or other appropriate person that an infectious measles case has attended their setting.
• Provide information and advice about measles ensuring access to accessible or appropriate language version, as required.
• Request information to inform risk assessment and contact tracing including:
  • dates and times the case was in attendance during their infectious period; obtain appointment or admission records, attendance records or rosters when available 
  • characteristics of the setting including size/dimensions
  • a list of all attendees, including staff and visitors and their contact details.
• Identify and manage close contacts; for most exposure events public health services will communicate directly with the close contacts (except for correctional or healthcare facilities (refer to operational guidance for management of specific settings (external link)).
• Support communication to those connected with the setting (e.g. staff and visitors).
• Protect case’s privacy by ensuring personal details are not included in communications.

Implementing other control measures

Publishing a location of interest

Publishing a location of interest should be considered if getting a complete list of attendees at an exposure event is not possible, or urgent communication is needed because the quarantine/restriction period for contacts has already started.

Public health services should inform the key contact person for the exposure event before a location of interest is published.

Publishing a location of interest can be supported (or substituted) by any, or all, of the following.

• A media release.
• Social media posts.
• Group text messaging or emails. 

Requests to publish a location of interest will be dependent on capacity of operational teams and should be sent to protection.clinical@tewhatuora.govt.nz and NISoperations@tewhatuora.govt.nz.  

For more information refer to:

Locations of Interest - PHS Process  (external link)

NDMS: How do I assign a Location of Interest Request to the National Investigation Service? | Knowledge | Salesforce (external link)

Ring vaccination

Public health services should identify exposure events where ring vaccination for connected settings could be considered. Implementing ring vaccination is not the responsibility of case and contact management teams, so supporting information should be provided to the relevant team (i.e. immunisation team) within the public health service or the relevant regional team for their consideration.

Guidance for ring vaccination is currently being developed, and a link to this guidance will be added when this is available.

For further information on ring vaccination contact protection.clinical@tewhatuora.govt.nz. 

Exposure events identified outside of the quarantine period for any contacts

Management of exposure events identified outside of the quarantine period for any contacts should be guided by the risk assessment. Engagement with the setting for active case finding may be required for some high-risk settings. Providing messaging to potential contacts advising of the exposure and the importance of monitoring for symptoms for 21 days after exposure may be the only action required. 

Detailed operational guidance for the following specific settings is available here (external link).

• Healthcare settings.
• Flight/airport.
• Education settings.
• Cultural associated and religious settings.
• Correctional facilities.
• Shared accommodation.

Key information about healthcare and flight exposure events is provided below.

Healthcare settings

Healthcare settings are common places for measles exposures to occur as cases present with symptoms prior to diagnosis.

When measles exposures occur in a hospital setting, the infection prevention and control team and occupational health services work closely with the public health service and have a key role in risk assessment and identifying and managing close contacts who are inpatients and healthcare workers.

Refer to Healthcare settings (external link) for more information about managing exposure events in healthcare settings. 

Contact tracing scope

Public health services should ensure contact tracing considers staff (including cleaners and support staff), patients and their accompanying caregivers/whānau/visitors who were present at the same time as the case and for up to 1 hour after the case left the area or was placed in appropriate isolation precautions. This time can be adjusted at the discretion of the medical officer of health or infection prevention and control lead. Refer to Classification of contacts by level of exposure and Healthcare settings (external link) for more information.

Flight exposure events

Flights pose a significant risk for widespread transmission due to the potential for passengers to rapidly disperse. During ‘stamp it out’, individual contact tracing is recommended for all domestic and international flights. 

All flight contact tracing for measles should be discussed with the medical officer of health on-call from the Protection Clinical team.

Contact tracing scope

International flights and large domestic flights (e.g. jets with appropriate ventilation/environmental control systems)

The recommended scope for contact tracing is passengers in the same row as the case as well as in the 8 rows in front of and behind the case (i.e. 17 rows in total). Cabin crew and pilots should be individually assessed to ascertain whether they may be classified as close contacts.

Consider extending the scope to the whole section of the plane (e.g. the whole of business class) or the whole flight, if there are no physical barriers separating sections of the plane if any of the following apply.

• The case moved around the aircraft
• There was more than one case.
• The case’s seat number cannot be determined in a timely manner.

Small domestic flights (e.g. turboprop planes without appropriate ventilation)

The recommended scope for contact tracing is all passengers and cabin crew on the flight because of differences in ventilation and smaller size of domestic flights. Pilots should be individually assessed.

Refer to Flight/Airport (external link) for more information about managing flight and airport exposure events.

An outbreak of measles is defined as 2 or more epidemiologically linked cases occurring within 1 incubation period of each other (i.e. the second case occurs between 7 and 21 days of the first case).

While a single case of measles does not meet the outbreak definition an urgent public health response is required due to the potential for a single case to result in an outbreak (refer to spread of infection).

The overarching goal of Aotearoa New Zealand’s response activities is to eliminate measles. Three outbreak phases have been described (for more information refer to the measles toolkit (external link)) for measles, with Aotearoa New Zealand currently in the ‘stamp it out’ phase. This section will be updated, as required, if a decision is made to change phases, noting that all efforts should be made to return to ‘stamp it out’ as soon as possible.

Additional goals are to:

• interrupt measles transmission and prevent future outbreaks
• prioritise equitable approaches during a response to improve health outcomes among priority groups
• minimise the impact of measles on whānau, the community and the health system.

The specific response objectives for measles are as follows.

• Provide effective and culturally appropriate public health management of cases, contacts and exposure events. This includes early identification and isolation of cases, and quarantine of non-immune close contacts.
• Provide appropriate support for isolation and quarantine.
• Deliver ring vaccination (external link) where appropriate.
• Increase awareness about measles among clinicians to promote notification of suspected cases, testing and appropriate isolation of cases.
• Ensure access to diagnostic consultations and testing for suspected cases.
• Maintain sufficient surveillance capability to rapidly detect cases and outbreaks.
• Communication and engagement with key stakeholders and the community.
• Monitor outbreak epidemiology and impact of response on priority populations

Management of local outbreaks

Individual cases and outbreaks will be managed by the local medical officer of health with support from regional and/or national teams as required.

The occurrence of an outbreak does not always indicate a significant increase in risk to the wider community. An assessment of risk will be made by the medical officer of health in consultation with regional and/or national teams as appropriate.

All outbreaks should be entered into EpiSurv and given an outbreak number. 

Refer to the notification and reporting section for notification and national escalation requirements.

National support and coordination

Support from national teams is always available. Requests for support with response activities should occur early in a response, before local and regional capacity is exceeded (refer to Appendix 5: Escalation Pathways).

A measles response must be nationally coordinated when cases, contacts, exposure events or outbreaks cross regional boundaries. National coordination will be activated following a discussion (usually an Initial Assessment Team meeting) between local and national teams (refer to Nationally coordinated response plan for outbreaks of communicable disease (external link)).

Determining when an outbreak is over

An individual outbreak can be considered over once there have been no new cases for 42 days (2 maximum incubation periods) since the last day of the infectious period of the most recent case, or the date the case was isolated. 

For more information

Refer to the following documents for more information.

• The Nationally coordinated response plan for outbreaks of communicable disease (external link) for guidance on a nationally coordinated response.
• The ESR guidelines (external link) for the investigation and control of disease outbreaks for a comprehensive guide on outbreak investigation and management.

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We would like to acknowledge the effort, contribution and commitment of all members of the Measles Clinical and Technical Advisory Group who have supported this work. Refer to Measles CTAG membership (external link) for a full list of members.