Seroprevalence of immunity to hepatitis A and hepatitis B among gay, bisexual and other men who have sex with men (GBMSM) attending sexual health clinics in London and Leeds, England, 2017-2018.

Objectives: Although hepatitis A virus (HAV) and hepatitis B virus (HBV) immunisation is recommended in the UK for gay, bisexual and other men who have sex with men (GBMSM), data on immunisation coverage are limited. We aimed to determine the seroprevalence of HAV and HBV immunity among a sample of GBMSM attending sexual health services (SHS) in England.

Methods: Residual serum samples from HIV/syphilis testing for adult GBMSM attending eight SHS in London and one in Leeds were tested for markers of HAV immunity (HAV IgG) and HBV immunity (anti-HBs) using an unlinked anonymous approach. We estimated seroprevalence of HAV and HBV immunity overall and stratified by individuals' characteristics, which we obtained from the Genitourinary Medicine Clinic Activity Dataset Sexually Transmitted Infection (STI) Surveillance System. We used logistic regression to calculate crude and adjusted ORs between seropositivity and demographic and clinical characteristics.

Results: Seroprevalence of immunity to HAV (74.5% of 2577) and HBV (77.1% of 2551) was high. In adjusted analysis, HAV IgG seroprevalence varied by clinic and WHO region of birth (global p<0.001 for each), increased with older age (ORs of 1.50 (95% CI 1.18 to 1.86), 2.91 (2.17 to 3.90) and 3.40 (2.44 to 4.75) for ages 26-35, 36-45 and >46 vs 18-25 years (global p<0.001), was higher in those with an STI in the past year (1.58 (1.25 to 2.00); p<0.001) and those who were living with HIV (1.82 (1.25 to 2.64); p<0.001). Anti-HBs seroprevalence varied by clinic (global p<0.001), increased with older age (global p<0.001) and was higher in those with an STI in the past year (1.61 (1.27 to 2.05); p<0.001).

Conclusion: Our findings provide a baseline seroprevalence from which to monitor serial levels of immunity to HBV and HAV in GBMSM accessing SHS. Levels of immunity for both viruses are high, noting samples were taken after recent widespread outbreaks and vaccination campaigns. High vaccine coverage in all GBMSM should be maintained to prevent further outbreaks.