At the 2010 ICAAC, it was reported that an extra "booster" dose of the hepatitis A virus (HAV) vaccine may be needed for HIV-positive men who have sex with men (MSM). This is to get a vaccine antibody response equal to what was seen in HIV-negative MSM.
HIV-positive MSM are generally 3 times more likely to get hepatitis A than their HIV-negative counterparts. It's currently recommended that all HIV-positive people get the HAV (and HBV) vaccine to protect them from serious illness. However, it's known that people with CD4 counts below 200 have poorer responses to vaccines in general. A study in Taiwan studied giving a booster dose of HAV vaccine to 476 MSM.
A total of 187 HIV-negative men got two doses of the vaccine at 0 and 6 months, as did 135 HIV-positive men. Another 154 HIV-positive men got three doses, at 0, 1 and 6 months. Levels of antibodies were checked at the study start, just before the 6-month dose and then 6 months after that.
Results showed that the levels of antibodies just before the 6-month dose were significantly lower in HIV-positive men. Only 39% of the HIV-positive men who took two doses compared to 63% of the negative men showed an antibody response by 6 months. However, those HIV-positive men who took the booster dose at 1 month had a similar response rate to HIV-negatives at 65%. Those men with CD4s below 200 who got 2 shots showed very poor response rates.
However, somewhat at odds with the results, the researchers didn't also report on the response rates of the men with CD4s below 200 who got 3 shots nor on the response rates that were seen 6 months after all the doses were given compared across all groups.