Hepatitis A Vaccine Breakthrough Infections Are Rare

A new study recently stated Hepatitis A (HepA) breakthrough infections after full hepatitis A vaccination are rare and appear more common in immunocompromised individuals (ICP).

Published in the December 2025 edition of the International Journal of Infectious Diseases journal, this systematic review and meta-analysis summarized documented HepA breakthrough infections among previously vaccinated individuals, 1991-2024.

Of 3345 reports screened, 90 were included, reporting 43,861 HepA cases, including 832 (partially) vaccinated.

These researchers identified six confirmed breakthrough infections with proof of complete vaccination (6.4%; 95% confidence interval 2.6-14.3%), including four ICPs (67%).

Post-vaccination serology was available in 3/6 cases: two HIV-positive patients were seronegative, and one neutropenic leukemia patient was seropositive but pauci-symptomatic.

The pooled proportion of ICPs among confirmed HepA cases was 17.8% (95% confidence interval 7.7-35.9%).

The study team wrote, 'Whenever possible, vaccination should be completed before the age of 40 and before immunosuppression.'

This finding aligns with the World Health Organization's position on HepA vaccination, which recommends a two-dose schedule for adults aged >40 years and ICPs, as there is insufficient evidence on the immunogenicity of a single dose in these groups.

The U.S. CDC says HepA is spread when someone ingests the virus, even in minimal amounts. This usually occurs through person-to-person contact or by eating or drinking contaminated food or drink. Over the last few years, HepA outbreaks have occurred in the United States.

In Europe, several countries have experienced outbreaks in 2025, with two clusters involving closely related HAV subgenotype IB strains.

The best way to prevent hepatitis A is to get vaccinated. You need to get all the shots in the series to be fully protected, says the CDC.

In the U.S., HepA vaccines are offered at clinics and community pharmacies as of November 20, 2025.