Within the UK, the majority of hepatitis A occurs in high risk groups such as men who have sex with men (MSM). It has been estimated that 70% of MSM need immunity to provide adequate herd immunity. We aimed to estimate the proportion of hepatitis A susceptibility in MSM throughout a 10-year period (2010-2019), and explore associated demographic factors. Using our Electronic Patient Record system, we extracted anonymous clinical data between for MSM at their first attendance; including hepatitis A IgG result, age, country of birth and diagnosis of an STI. Overall, 1401/6884(20%) were tested for hepatitis A IgG at their first attendance, with 626/1401 (45%, 95% CI = 42%-47%) showing susceptibility. Testing rates increased between 2010-2019 (OR = 67.79, 95%CI = 39.09-117.60, p = <0.0001); however, susceptibility remained similar (OR = 0.98, 95%CI = 0.33-2.89, p = 0.98). MSM aged 35 and under had significantly higher susceptibility vs MSM aged over 35 (OR 3.4176, 95%CI = 2.71-4.31, p = <0.0001). UK-born had significantly higher susceptibility vs non-UK born (OR 1.5, 95%CI = 1.2147-1.8618, p = 0.0002). Susceptibility of hepatitis A in MSM may be higher than necessary to control future outbreaks. It is important that effective targeting of MSM, particularly young MSM, occur at all levels of healthcare and not solely rely on opportunistic presentation at a sexual health clinic.
Keywords: Hepatitis A; men who have sex with men; susceptibility; vaccination threshold.