A recent study (PR Spradling et al. Hepatology 2016; 63: 703-11) provided data indicating that the Hepatitis A virus (HAV) vaccine would likely work for 30 years after childhood vaccination. Much has changed since the implementation of the HAV vaccine. Since 2000, the number of HAV case in the U.S. has dropped almost 90%, from 13,397 to 1781 in 2013 with the lowest incidence in those ≤18 years.
This study (n=183) examined three groups of Alaska Native children who received a two-dose inactivated HAV vaccine.
- Vaccine starting at age 6 months (group 1)
- Vaccine starting at age 12 months (group 2)
- Vaccine starting at age 15 months (group 3)
- All participants in groups 2 and 3 through age 10 years were seropositive (anti-HAV ≥ 20 mIU/mL), whereas in group 1 it was >90%.
- At 15-16 years following vaccination, the seropositivity was 50-75% in group 1 and 67-87% in groups 2 and 3.
- Using modeling, the overall 30-year anti-HAV seropositivity was predicted to be present in 64% of all participants and 84% of those that were seropositive at 15-16 years.
HAV continues to represent an ongoing threat, despite a reduction in the number of cases. This is particularly due to unvaccinated travelers and unvaccinated adutls. In vaccinated adults, a study (Vaccine 2015; 33: 5723-27) inidcates that seropositivity would be present in at least 95% after 30 years and 90% after 40 years.
My take: these data provide reassurance that HAV vaccine’s protection will be durable among those who were vaccinated between 6-21 months of life.
Related blog posts:
- What’s Going on with Hepatitis A and Hepatitis B? | gutsandgrowth
- Hepatitis A vaccine immunity -will it last? | gutsandgrowth