A dose of hepatitis A vaccine or immune globulin (IG) given within two weeks of exposure prevents infection with hepatitis A virus. In February 2018, the Advisory Committee on Immunization Practices (ACIP) voted unanimously, 14 to 0, to lean on the vaccine: for everyone 12 months and older after an exposure, and for babies 6 to 11 months old before international travel.
What changed
| Before | From 2018 | |
|---|---|---|
| After exposure, ages 1–40 | vaccine | vaccine |
| After exposure, over 40 | IG (vaccine if IG unavailable) | vaccine, plus IG if the provider judges it needed |
| Infants 6–11 months traveling abroad | IG — which cannot be given with the recommended MMR vaccine | hepatitis A vaccine, given with MMR |
| IG dose | — | updated to 0.1 mL/kg where applicable |
Why vaccine
Compared with IG, the vaccine builds the body's own (active) immunity, protects longer, is easier to give, and is more widely accepted and available. The old preference for IG in adults over 40 assumed it worked better in them — but IG's potency had declined, leading in 2017 to a larger recommended dose and so a larger injection. When exposure is uncertain — someone who ate a recalled food, or ate at a restaurant that issued a notice — long-lasting vaccine protection makes even more sense.
The evidence: in a randomized, double-blind trial of 1,090 susceptible contacts aged 2 to 40, vaccine given within 14 days of exposure performed nearly as well as IG in healthy people under 40. Data for adults over 40 are limited and suggest a weaker response to vaccine with age.
For infants, IG blocks the response to measles and rubella vaccines for three months. Since MMR is recommended for all infants 6 to 11 months traveling abroad, and measles in infancy is more severe than hepatitis A, MMR takes priority. Hepatitis A vaccine — used off-label in this age group — is safe and effective in babies as young as 2 months and can be given with MMR, protecting against both, though maternal antibodies may blunt the long-term response.
Recommendations after exposure
Give prophylaxis as soon as possible, and within 14 days; it has not been shown to work later.
- Healthy people 12 months and older who have not completed the two-dose series: one dose of vaccine. IG may be added for adults over 40, depending on the provider's assessment.
- People 12 months and older who are immunocompromised or have chronic liver disease: IG (0.1 mL/kg) and vaccine together, in different limbs. For long-term immunity, a second dose at least 6 months later.
- Infants under 12 months and people who cannot have the vaccine (for example, after a life-threatening allergic reaction to it): IG (0.1 mL/kg) instead. MMR and varicella vaccines should then wait at least 3 months.
- IG should also be considered for people with other special risk factors for infection or complications.
Recommendations before travel
For unvaccinated people traveling to or working in countries with high or intermediate hepatitis A levels:
| Traveler | Protection |
|---|---|
| Infants under 6 months, and anyone who declines or cannot have vaccine | IG: 0.1 mL/kg for trips up to 1 month, 0.2 mL/kg up to 2 months, and 0.2 mL/kg every 2 months for longer stays |
| Infants 6–11 months | one dose of vaccine; it does not count toward the routine series, which starts at 12 months |
| Healthy people 12 months–40 years | one dose of vaccine as soon as travel is considered, then complete the series |
| Adults over 40, immunocompromised people, people with chronic liver disease or other chronic conditions leaving within 2 weeks | first dose of vaccine, and IG may be given at the same time in another limb |
Sources
Based on "Update: Recommendations of the Advisory Committee on Immunization Practices for Use of Hepatitis A Vaccine for Postexposure Prophylaxis and for Preexposure Prophylaxis for International Travel," by Noele P. Nelson and colleagues, Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain. An erratum to the report has been published.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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