Hepatitis A vaccination during an outbreak among gay men in Montreal, Canada, 1995-1997

Study objective-To evaluate an intervention designed to curtail an outbreak of hepatitis A among gay men, especially the young and sexually active, by promoting their free vaccination. Design-The study analysed routine passive surveillance data, carried out qu estionnaire and serological surveys of vaccinees, and surveys among the tar get population in non-clinical venues. Setting and intervention-15000 free doses of hepatitis A vaccine were made available through clinics with large gay clienteles, or at gay events, and advertised by various means, in Montreal, Canada, from August 1996 to Novem ber 1997. Simultaneous vaccination against hepatitis B (always free for gay men) was also encouraged. Participants-Information was obtained from perso ns with the disease during the epidemic period, a sample of men requesting vaccination, and five community samples of gay men. Main results-The outbreak involved 376 gay men and the vaccine was distribu ted to approximately 10 000. Vaccinees were older than cases, but had many sex partners and comprised more food handlers. Special vaccination clinics at gay events were well attended but did not reach more high risk men than regular medical venues. A self reported vaccine coverage of 49% was achieve d, but 26% of vaccinees already had anti-HAV antibodies. Disease incidence declined rapidly during the campaign. Conclusions-The intervention nearly tripled self reported hepatitis A vacci ne coverage but its late start precludes proving that it caused the subsequ ent drop in incidence. However, it also increased hepatitis B vaccination a nd it is believed it improved links between gay men, public health, clinici ans and community groups.