7. Haemophilus influenzae type b (Hib) disease

The source of the organism is the upper respiratory tract. Immunisation with a protein conjugate vaccine reduces the frequency of asymptomatic colonisation by Hib. Before the introduction of the vaccine, Hib was the most common cause of bacterial meningitis in children. Worldwide immunisation coverage is increasing, with approximately 194 countries having fully or partially introduced Hib onto their schedules by July 2019 (98 percent of all WHO member states).[1] The estimated global coverage for three doses of Hib is 72 percent as of July 2019.[2]

Hib-PRP was introduced in 1994 (see Appendix 1). In 1993, 101 children aged under 5 years had laboratory-confirmed invasive Hib disease (an age-specific rate of 36.4 per 100,000 population). By 1999 only five children in this age group had laboratory-confirmed disease (1.7 per 100,000) (Figure 7.1).

Two cases of Hib were notified and laboratory confirmed in 2019 (ESR, 8 June 2020). The cases were aged 50–59 and 60–69 years, both were unvaccinated. There were seven deaths from Hib between 1997 and 2019 (ESR, 8 June 2020), the most recent was in 2012 in an adult over 70 years of age.[3]

Figure 7.1: Number of notifications and culture-positive cases of Haemophilus influenzae type b invasive disease, 1997–2019

Funded vaccines

Other vaccines

No other Hib vaccines are available currently. Hib-PRP-T (Act-HIB, Sanofi) was the funded vaccine prior to the 1 July 2017 Schedule change.

The high efficacy and effectiveness of Hib-PRP vaccines have been clearly demonstrated by the virtual elimination of Hib in countries implementing the vaccine,[4, 5, 6] including New Zealand. Hib-PRP vaccines are highly effective after a primary course of two or three doses.[7, 8, 9] Disease following a full course of Hib-PRP is rare.

Conjugate vaccines reduce carriage in immunised children and as a result also decrease carriage and disease in unimmunised people (herd immunity). These vaccines will not protect against infection with NTHi strains, and therefore do not prevent the great majority of otitis media, recurrent upper respiratory tract infections, sinusitis or bronchitis.

(See also section 15.4.2 for information about the DTaP‑IPV‑HepB/Hib vaccine.)

Duration of immunity

A primary series followed by a booster dose in the second year of life should provide sufficient antibody levels to protect against invasive Hib disease to at least the age of 5 years.[10]

Transport according to the National Standards for Vaccine Storage and Transportation for Immunisation Providers 2017 (2nd edition).

Store at +2°C to +8°C. Do not freeze. DTaP-IPV-HepB/Hib should be stored in the dark.

The dose of DTaP-IPV-HepB/Hib and Hib-PRP-T vaccines is 0.5 mL administered by intramuscular injection. Hib-PRP-T can also be administered subcutaneously if indicated (see section 2.2.3).

Co-administration

DTaP-IPV-HepB/Hib and Hib-PRP-T vaccines can be co-administered with other routine vaccines on the Schedule, in separate syringes and at separate sites.

Hib vaccine is funded for all children aged under 5 years. Three doses of DTaP-IPV-HepB/Hib (Infanrix-hexa) vaccine are given as the primary course, with a booster of Hib-PRP-T (Hiberix) at age 15 months (see Table 7.1).

Children

Because of an increased risk of infection, it is particularly important that the following groups of children, whatever their age, receive the Hib vaccine as early as possible (see also sections 4.2 and 4.3):

• children with anatomical or functional asplenia, or who are suffering from sickle cell disease (if possible, it is recommended that children be immunised prior to splenectomy)
• children with partial immunoglobulin deficiency, Hodgkin’s disease or following chemotherapy (note, however, that response to the vaccine in these children is likely to be suboptimal)
• children with nephrotic syndrome
• HIV-positive children.

Recommendations for Hib vaccine for older children and adults with asplenia

Although there is no strong evidence of an increased risk of invasive Hib disease in asplenic older children and adults, some authorities recommend Hib immunisation for these individuals.[11, 12] The Hib PRP-T vaccine has been shown to be immunogenic in adults.

• Hib-PRP-T vaccine (Hiberix) is funded for older children and adults pre- or post-splenectomy or with functional asplenia; one dose of vaccine is recommended (see also section 4.3.4) if childhood vaccine schedule is incomplete or unknown.

Note: Pneumococcal, meningococcal, influenza, varicella and pertussis-containing vaccines are also recommended for these individuals; see section 4.3 and the relevant disease chapters.

Children aged under 2 years with Hib disease do not reliably produce protective antibodies and need to receive a complete course of Hib-PRP-T. The number of doses required will depend on the age at which the first dose after the illness is given, ignoring any doses given before the illness (follow the age-appropriate catch-up schedules in Appendix 2).

Commence immunisation approximately four weeks after the onset of disease.

Any immunised child who develops Hib disease or who experiences recurrent episodes of Hib invasive disease requires immunological investigation by a paediatrician.

Hib-PRP-containing vaccines are funded for vaccination and revaccination of eligible patients, as follows. See also section 4.3.

DTaP-IPV-HepB/Hib (Infanrix-hexa)

Up to an additional four doses (as appropriate) of DTaP-IPV-HepB/Hib are funded for vaccination or revaccination of children aged under 10 years:

• post-HSCT or chemotherapy
• pre- or post-splenectomy
• pre- or post-solid organ transplant
• undergoing renal dialysis
• prior to planned or following other severely immunosuppressive regimens.

 Up to five doses of DTaP-IPV-HepB/Hib are funded for children aged under 10 years receiving solid organ transplantation.

Hib-PRP-T (Hiberix)

One additional dose of Hib-PRP-T (Hiberix) is funded for vaccination or revaccination of patients:

• post-HSCT or chemotherapy
• pre- or post-splenectomy or with functional asplenia
• pre- or post-solid organ transplant
• pre- or post-cochlear implants
• undergoing renal dialysis
• prior to planned or after other severely immunosuppressive regimens.

Hib-PRP is not routinely recommended for pregnant or breastfeeding women. However, for women with asplenia see the ‘Recommendations for Hib vaccine for older children and adults with asplenia’ in section 7.5.2.

Adverse reactions to Hib-PRP conjugate vaccines are uncommon. Pain, redness and swelling at the injection site occur in approximately 25 percent of recipients, but these symptoms typically are mild and last less than 24 hours.[13]

A meta-analysis of trials of Hib-PRP vaccination from 1990 to 1997 found that serious adverse events were rare.[14] No serious vaccine-related adverse experiences were observed during clinical trials of Hib vaccine alone. There have been rare reports, not proven to be causally related to Hib vaccine, of transverse myelitis, thrombocytopenia and Guillain-Barré syndrome (GBS).[15]

All child contacts should have their immunisation status assessed and updated, as appropriate.

Immunisation reduces – but does not necessarily prevent – the acquisition and carriage of Hib. Therefore, immunised children still need rifampicin prophylaxis, when indicated, to prevent them transmitting infection to their contacts. Careful observation of exposed household and early childhood service contacts is essential. Exposed children who develop a febrile illness should receive prompt medical evaluation.

Rifampicin chemoprophylaxis

To eradicate the carrier state and protect susceptible children, antimicrobial prophylaxis should be given to contacts as soon as possible, and ideally within seven days of the index case developing the disease, irrespective of their own immunisation status. Prophylaxis started after seven days may still be of benefit and is recommended. Note that the prophylaxis for Hib is different from that for meningococcal disease (see chapter 13).

Rifampicin recommendations

Chemoprophylaxis with rifampicin is recommended for the following contacts of an index case of Hib:

• all members of the case’s household (including adults) where there is at least one contact aged under 4 years who is either unimmunised or partially immunised
• all members of a household where there is a child aged under 12 months, even if the child has had three doses (primary series) of the Hib-PRP vaccine
• all members of a household where there is an immunosuppressed person
• all staff and children at an early childhood service where two or more cases of Hib have occurred within 60 days.

Use oral rifampicin 20 mg/kg (maximum 600 mg) daily for four days. The dose for infants aged under 4 weeks has not been established, but a dose of 10 mg/kg per day is recommended. This is a different regimen to that recommended for prophylaxis from meningococcal disease (see chapter 13).

The index case should also receive rifampicin unless treated with cefotaxime or ceftriaxone.

Rifampicin is not recommended for:

• occupants of households where there are no children aged under 4 years, other than the index case
• occupants of households where all contacts aged 12 months to under 4 years have completed their immunisation series, including the second-year-of-life dose
• pregnant women – rifampicin is contraindicated in pregnant women; pregnant women who are a household contact of an index case should receive ceftriaxone.

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2. World Health Organization ,UNICEF. 2019 Global and regional immunization profile. URL: https://www.who.int/immunization/monitoring_surveillance/data/gs_gloprofile.pdf?ua=1. (accessed 3 July 2020)
3. Institute of Environmental Science and Research Ltd. 2013. Notifiable and Other Diseases in New Zealand: Annual Report 2012 (ed.), Porirua: Institute of Environmental Science and Research Ltd. URL: URL: https://surv.esr.cri.nz/PDF_surveillance/AnnualRpt/AnnualSurv/2012/2012AnnualSurvRpt.pdf (accessed 3 July 2020)
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10. Khatami A, Snape MD, John TM, et al. Persistence of immunity following a booster dose of Haemophilus influenzae type B-meningococcal serogroup C glycoconjugate vaccine: follow-up of a randomized controlled trial. Pediatric Infectious Disease Journal, 2011. 30(3): p. 197–202.
11. Centers for Disease Control and Prevention. 2014. Prevention and control of Haemophilus influenzae type b disease: recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report: Recommendations and Reports. 63(RR-1): p. 1–14. URL: https://www.cdc.gov/mmwr/pdf/rr/rr6301.pdf (accessed 3 July 2020)
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