The study estimated the transmissibility of HAV during a hepatitis A outbreak among MSM living with HIV in Taiwan between 2015-2017, to measure the effectiveness of HAV vaccination in this population. A case-control study method was utilised to assess the effectiveness of HAV vaccination in MSM living with HIV.
Acute hepatitis A was defined as a documented anti-HAV IgM, with clinical symptoms, elevated aminotransferases, or jaundice. Since 30% of HIV-positive MSM had mild symptoms after Hepatitis A exposure, they estimated the basic reproductive number as high as 6.37 during this outbreak. 55 cases of acute hepatitis A were identified among 1533 initially HAV seronegative HIV-positive MSM. Median age was 30 years old and baseline CD4 count of 545 cells/µL, and 60% had recent syphilis within 6 months prior to the onset of acute hepatitis A.
HIV-positive MSM who were vaccinated to Hepatitis A were protected from acute Hepatitis infection with an overall vaccine effectiveness of 97.4%. When compared between a single dose to a two doses Hepatitis A vaccination, it was 96.1% and 99.7%, respectively. This study finding suggest that the high individual level vaccine effectiveness in MSM living with HIV might have contributed to the rapid control of this outbreak in Taiwan. Hence, the findings strongly support for the implementation of HAV vaccination among MSM living with HIV to better control such outbreaks in this key population.
Although, HIV-positive individuals are offered funded vaccinations within the context of a sexual health clinic, there is no free funded HAV vaccination in Australia for the MSM community regardless of their HIV status outside of an outbreak risk management intervention. Anal sex and oral-anal contact during sexual activities are risk factors in this key population in terms of Hepatitis A exposure. Therefore, Hepatitis A vaccine should be listed in the National Immunisation Program Schedule for all MSM regardless of their HIV status. It will provide herd immunity for the general population and will also be a very cost-effective measure to the overall healthcare system.
