Increasing hepatitis A IgG prevalence rate in men who have sex with men attending a sexual health clinic in London: implications for immunization policy

The aims of this study were to audit an immunization policy to vaccinate men who have sex with men (MSM) attending a large London sexual health clinic, and to undertake an approximate cost analysis of different strategies, using the estimated prevalence rate of anti-hepatitis A virus (HAV) immunoglobulin G (IgG). A retrospective study of the seroprevalence of anti-HAV IgG among MSM was conducted for a 12-month period, involving 395 homosexual or bisexual men attending the genitourinary medicine clinic at St Mary's Hospital, London, for the first time. Overall seroprevalence of anti-HAV IgG in the 2004 population surveyed was 46.6% (140/300); 75.1% (300/395) were offered screening on their first visit and 49.9% (197/395) were offered vaccination. We concluded that anti-HAV IgG screening prior to vaccination of MSM in an area of relatively low prevalence of HAV is still the most cost-effective approach. The audit data also showed that in 2004 the British Association for Sexual Health and HIV targets for hepatitis A screening and vaccination were not reached. If a onedose policy is seen to establish long-term immunity, then the cost of hepatitis A prevention will be drastically reduced.