Hib Vaccine Side Effects (Haemophilus influenzae type b — AE Database Reports)

1. Basic Information

Disease Protected Against

Haemophilus influenzae type b (Hib) is a bacterial pathogen that primarily affects children <5 years. Before vaccination, Hib was the leading cause of bacterial meningitis in U.S. children, as well as epiglottitis, septic arthritis, pneumonia, and bacteremia. Hib meningitis has a case-fatality rate of ~3–6% and causes permanent neurological sequelae (hearing loss, developmental delay) in 15–30% of survivors. Nontypeable H. influenzae (NTHi) strains, which are not covered by the Hib vaccine, cause otitis media and respiratory infections in children and adults but not invasive disease at the same rates.

CDC Recommended Schedule (U.S., 2025)

Source: CDC ACIP, 2025 Child & Adolescent Immunization Schedule. Note: PedvaxHIB (Merck, PRP-OMP conjugate) requires only a 2-dose primary series at 2 and 4 months plus a booster at 12–15 months.

Licensed Products (U.S.)

• ActHIB^® (Sanofi) — PRP-T conjugate (tetanus toxoid carrier). Licensed 1993.
• Hiberix^® (GSK) — PRP-T conjugate. Licensed 2009, primarily for booster dose.
• PedvaxHIB^® (Merck) — PRP-OMP conjugate (outer membrane protein carrier). Licensed 1989. 2-dose primary series.
• Combination vaccines: Pentacel (DTaP-IPV-Hib), VAXELIS (DTaP-IPV-Hib-HepB). Both use PRP-T conjugate.

Ingredients (Package Insert)

Structured composition for 3 branded products covered on this page, taken from FDA-approved package inserts (DailyMed / manufacturer prescribing information). Lists are per product — formulations differ by manufacturer and presentation. Click an ingredient name to open its safety-context page when available.

Causality assessment & potential mechanisms

Conditions below combine WHO-style causality levels with potential biological mechanisms from the site mechanism catalog (ae_mechanisms_catalog.json). HRSA VICP table listing (where shown) indicates a compensable temporal association under U.S. program rules — not automatic proof of causation for every case. Mechanisms are hypothesis-level pathways with graded evidence.

Framework: WHO causality + HRSA VICP (where applicable) + AE mechanism catalog. Last updated: 2026-07-18. Schema: schemas/vaccine_injury_table.schema.json · Mechanisms: schemas/ae_mechanism.schema.json. Not medical or legal advice.

2. Pre-Licensure Clinical Trial Data

The first Hib polysaccharide vaccine (unconjugated) was licensed in 1985 but was poorly immunogenic in infants <18 months. The first conjugate vaccine (PRP-D, ProHIBIT) was licensed in 1987. Current PRP-T and PRP-OMP conjugate vaccines were licensed between 1989–1993. Pivotal trials enrolled several thousand infants each.

Most Common Adverse Reactions

Sources: Respective prescribing information; FDA review documents. Adverse reactions are generally mild and self-limited (1–3 days). Local reaction rates are higher when Hib is given as part of combination vaccines (Pentacel, VAXELIS).

Key Limitations

• No true placebo: Most trials used other vaccines as comparators due to ethical constraints, limiting absolute risk attribution.
• Combination products: Modern Hib vaccination is predominantly via combination vaccines (Pentacel, VAXELIS), making it difficult to isolate Hib-specific adverse events from those attributable to co-administered antigens (DTaP, IPV).
• Carrier protein effects: Different Hib conjugates use different carrier proteins (tetanus toxoid, OMP). The long-term safety implications of repeated carrier protein exposure in combination schedules are not fully characterized.

3. Post-Licensure Safety Data

VSD and VAERS

Hib vaccines have an extensive post-licensure safety record with >30 years of U.S. data. VSD and VAERS surveillance have not identified unexpected safety signals. Key findings:

• No association between Hib vaccination and serious adverse events, SIDS, or neurodevelopmental outcomes has been identified in VSD studies.
• VAERS data are consistent with clinical trial reactogenicity profiles. No confirmed safety signals beyond those identified in pre-licensure trials.
• IOM (2012) reviewed Hib vaccine and found evidence inadequate to accept or reject causality for most rare outcomes, reflecting the low frequency of adverse event reports and limited targeted post-licensure studies (relative to more controversial vaccines).

VAERS Reporting Data — Halma & Varon (2025), DARE-SAFE

The DARE-SAFE paper (Halma & Varon, Pharmacoepidemiology 2025, CC BY 4.0) analyzed VAERS reports for vaccines administered in the United States from 2006–2022. The following data are extracted from Table 1 of that paper for this vaccine (HiB (all Hib products combined)):

Source: Halma, M.; Varon, J. DARE-SAFE. Pharmacoepidemiology. 2025. DOI: 10.3390/pharma4020007. CC BY 4.0. Data from Table 1.

Passive Surveillance: AE Type Breakdown (Multi-System)

Side-by-side view of U.S. VAERS, Health Canada Canada Vigilance, Japan JADER (PMDA), EU EudraVigilance, and live-scraped international systems via SurVigilance (VigiAccess, Lareb, DAEN, DMA, Medsafe). SurVigilance panels show MedDRA PT mention totals (not individual-case counts). Category assignment uses keyword matching — approximate, not official SOC coding. VAERS ZIP CAPTCHA downloads use this site’s vaers_pipeline.py; FAERS is bulk quarterly ZIP via SurVigilance (not product search).

SurVigilance: VigiAccess · Lareb · DAEN · DMA · Medsafe

Compare AE patterns across all vaccines →

4. Documented Adverse Events

▶ Strong Evidence

• Injection site reactions: Pain (10–25%), redness/swelling (5–10%). Mild, self-limited. Strong
• Fever: 5–15% (low-grade). Strong
• Irritability/drowsiness: 15–30%. Self-limited (1–2 days). Strong
• Anaphylaxis: ~1 per million doses (rare). Strong

▶ Published Evidence Does Not Support a Causal Association

• SIDS: No association. No Association
• Type 1 diabetes: Studied; no association found. No Association

5. Disease Prevention Benefits

Source: CDC Pink Book; MMWR. The Hib vaccine has near-eliminated invasive Hib disease in the U.S. Vaccination also reduces nasopharyngeal carriage, providing herd protection to unvaccinated children.

Disease Burden Over Time

Reported U.S. disease burden by year. The dashed vertical line marks vaccine introduction. Hover or tap data points for values; use arrow keys when a chart has focus.

7. Evidence Summary

Hib conjugate vaccines have been in U.S. use for >35 years with a well-established safety and effectiveness profile. Pre-licensure trials were moderate in size but post-licensure data from national surveillance and VSD are extensive. The Hib vaccine is among the most effective in the pediatric schedule, with >99% reduction in invasive disease. No significant post-licensure safety signals have been identified.

8. International Surveillance & Global Data

Quick links to public pharmacovigilance databases and trial registries relevant to Hib Vaccine. Reporting counts do not establish causality.

9. Curated Adverse Event Literature

Curated peer-reviewed literature linking specific adverse events to Hib Vaccine. Each entry is a case report, case series, or related safety publication identified via PubMed. Expand Search PubMed for additional literature below to run custom queries.

10. Key References

1. IOM. Adverse Effects of Vaccines: Evidence and Causality. National Academies Press; 2012. nationalacademies.org
2. CDC. Pink Book — Hib chapter. cdc.gov/pinkbook
3. Peltola H. Worldwide Haemophilus influenzae type b disease at the beginning of the 21st century. Clin Microbiol Rev. 2000;13(2):302–317.
4. CDC. VSD. cdc.gov/vaccine-safety/about/vsd.html
5. CDC/FDA. VAERS. vaers.hhs.gov