Background Recent outbreaks of hepatitis A have been reported globally, and increasing numbers of cases and deaths are being reported in Australia, particularly among men who have sex with men (MSM). The critical vaccination threshold for hepatitis A has been estimated to be ≥70% to prevent outbreaks in MSM. This study aimed to determine the level of immunity to hepatitis A among MSM since 2012.

Methods This was a retrospective audit of serological testing data from first-time MSM attendees at the Melbourne Sexual Health Centre (MSHC) from 2012–2018. We determined the proportion of MSM who were tested and who had serological detection of hepatitis A antibodies, stratified by age and year. We used logistic regression to investigate factors associated with detection of hepatitis A antibodies.

Results There were 16,615 new MSM attendees at MSHC over the 7-year period, of which 9,719 (58%, 95%CI:57,59%) were tested for hepatitis A antibodies. There was a 2% annual increase in the proportion of men tested over time (from 60% in 2012 to 69% in 2018;p=0.025). Of those tested, 44% (n=4,304, 95%CI:43,45%) of men had hepatitis A antibodies detected at their first visit, but there was no change over time (p=0.201). However, compared to our last audit that spanned 2002–2011, a higher proportion of young MSM (aged <20 years) were tested for hepatitis A at their first visit (73% vs 33% before 2012) and had antibodies detected (38% vs 19% before 2012). Detection of hepatitis A antibodies was associated with age ≥30 (Adjusted OR=1.89, 95%CI:1.77,2.02), being born overseas vs Australia/New Zealand (AOR=1.23, 95%CI:1.13,1.33), and consistent condom use in the last 12 months (AOR=1.19, 95%CI:1.12,1.28).

Conclusion Hepatitis A immunity amongst MSM remains far below the estimated 70% required to prevent outbreaks. Measures including increased testing and higher vaccination coverage are needed to limit the number of cases and deaths.

Disclosure No significant relationships.