Hib Vaccines for American Indian and Alaska Native Infants: ACIP Adds Vaxelis, 2024

Invasive Haemophilus influenzae type b (Hib) disease is a serious bacterial infection that hits American Indian and Alaska Native (AI/AN) people disproportionately — before Hib vaccines and since. Before 1985, Hib was the leading cause of bacterial meningitis in U.S. children under 5; after effective vaccines arrived (polysaccharide vaccines in 1985, conjugate vaccines in 1987), invasive Hib disease in that age group fell by more than 99%.

Why AI/AN infants have had a preferred vaccine

• Before routine vaccination, Hib meningitis peaked younger in AI/AN infants — at 4–6 months — than in other U.S. infants (6–7 months).
• The five Hib conjugate vaccines licensed in the United States join the Hib capsular polysaccharide (PRP) to either an outer membrane protein complex of Neisseria meningitidis serogroup B (PRP-OMP) or tetanus toxoid (PRP-T).
• Monovalent PRP-OMP (PedvaxHIB, Merck) gives a protective antibody response after the first dose, at 2 months; PRP-T vaccines don't. So PRP-OMP has been preferred for AI/AN infants, for earlier protection.
• Vaxelis (DTaP-IPV-Hib-HepB, MSP Vaccine Company, a Merck–Sanofi partnership) is a six-in-one vaccine — diphtheria, tetanus, pertussis, polio, Hib and hepatitis B — whose Hib part is also PRP-OMP. It had not been included in the preference, because its PRP-OMP dose is lower than PedvaxHIB's and there were no data on protection after its first dose.

How the decision was made

From December 2023 to June 2024, the Advisory Committee on Immunization Practices (ACIP) Meningococcal/Hib Vaccines Work Group reviewed Hib disease among AI/AN people and new trial data. In January 2024, CDC held a listening session with tribal communities and Indian Health Service staff. ACIP weighed the question — should Vaxelis join PedvaxHIB in the preference? — using its Evidence to Recommendations framework (the problem, benefits and harms, the population's values, acceptability, resources, equity, feasibility) and GRADE to rate the evidence.

The evidence

A randomized trial compared the two vaccines in 333 Navajo Nation and Alaska Native infants — healthy, born at 35 weeks or later, and aged 42–90 days at their first shot. One group got Vaxelis at 2, 4 and 6 months; the other PedvaxHIB at 2 and 4 months. There were no data on actual Hib disease.

The most common serious adverse event was acute respiratory infection (21 of 25), and none was judged related to the study. The Work Group found every part of the framework supported adding Vaxelis.

The recommendation (June 26, 2024)

Vaxelis joins PedvaxHIB in the preferred recommendation for AI/AN infants, because of its PRP-OMP Hib component.

Primary series — preferred for AI/AN infants:

• PedvaxHIB: 2 doses, at 2 and 4 months; or
• Vaxelis: 3 doses, at 2, 4 and 6 months.

If the first Hib dose is more than a month late, follow the catch-up schedule.

Booster:

• Vaxelis is only for infants at 2, 4 and 6 months — not for the Hib, DTaP or IPV boosters.
• No vaccine is preferred for the AI/AN Hib booster (at 12–15 months): use any Hib vaccine except Vaxelis.
• Clinics serving AI/AN children could stock PedvaxHIB for the booster, which keeps it available as a primary-series choice; a PRP-T vaccine is also an option. In a phase 3 study, 124 AI/AN infants given Vaxelis and then a PRP-T booster had a robust immune response.
• If Vaxelis is given by mistake as a booster, the dose need not be repeated as long as doses are properly spaced.

Reporting side effects

Report any adverse event after vaccination to the Vaccine Adverse Event Reporting System (VAERS), even if unsure the vaccine caused it — at vaers.hhs.gov or 800-822-7967. Reports from the Indian Health Service Federal, Tribal and Urban system should write "IHS" in item 26 of the form.

Sources

Based on Collins JP, Loehr J, Chen WH, Clark M, Pinell-McNamara V, McNamara LA, "Use of Haemophilus influenzae Type b–Containing Vaccines Among American Indian and Alaska Native Infants: Updated Recommendations of the Advisory Committee on Immunization Practices ― United States, 2024," MMWR Morbidity and Mortality Weekly Report, volume 73, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The source's "DTtaP" is corrected to DTaP.