SUMMARY: People with HIV require 3 doses of hepatitis A virus (HAV) vaccine to achieve the same level of antibody protection that HIV negative people can get with 2 doses, according to a study presented at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010) last month in Boston. HAV antibody response was particularly weak among HIV positive men with a CD4 count below 200, all of whom needed the third vaccine booster dose.

By Liz Highleyman

Hepatitis A is spread through contaminated food and water, as well as household contact and some types of sexual activity. It can cause flu-like symptoms and jaundice, but it resolves without treatment; unlike hepatitis B and C, it does not cause liver fibrosis or lead to cirrhosis or liver cancer.

Hepatitis A immunization (vaccine)

Studies have shown that men who have sex with men (MSM) are at increased risk for hepatitis A, and the Centers for Disease Control and Prevention (CDC) recommends that HIV positive MSM should be screened for HAV and vaccinated if not previously infected.

Yu-Tzu Tseng from Taipei City Hospital and colleagues conducted a study to determine optimal hepatitis A vaccine dose schedules for HIV positive gay/bisexual men in the era of highly active antiretroviral therapy. People with seriously compromised immune systems -- as indicated by a low CD4 cell count -- may not be able to produce enough antibodies in response to a vaccine, but outcomes in HIV positive people with well-preserved immune function have not been well studied.

The present analysis included HIV positive and HIV negative MSM under 40 years of age enrolled between June 2009 and April 2010 at HIV clinics and counseling and testing sites in Taiwan.

Participants were first screened for hepatitis A IgG antibodies. Men found to be HAV seronegative were given 2 doses (administered at baseline and 6 months) or 3 doses (at baseline, 1 month, and 6 months) of hepatitis A vaccine. Among participants who consented to vaccination, 140 HIV positive men and all HIV negative men received 2 doses, while 178 HIV positive men received 3 doses.

Anti-HAV antibodies titres were measured at 6 months (just before the final vaccine dose was administered) and again after 12 months.

Results

	At baseline, hepatitis A virus seroprevalence was more than twice as high among HIV positive men as among HIV negative men, 15% vs 7%, respectively.
	At 6 months, before the final vaccine dose, HIV positive men who received 1 previous dose were less likely to have mounted an antibody response than either HIV positive men who received 2 prior doses or HIV negative men:
	HIV positive, 1 dose: 38% HAV seroconversion; HIV positive, 2 doses: 63% seroconversion; HIV negative, 1 dose: 57% seroconversion.
	HAV seroconversion rates were significantly higher among HIV positive men with CD4 cell counts > 200 cells/mm3 compared to those with lower counts:
	2-dose group at 6 months: 40%; 2-dose group at 12 months: 70%; 3-dose group at 6 months: 50%; 3-dose group at 12 months: 90%.
	In contrast, none of the HIV positive men with CD4 counts < 200 cells/mm3 achieved an HAV antibody response at 6 or 12 months with only 2 vaccine doses.

At 6 months after starting the vaccination process, "HIV-infected MSM receiving 2 [more] doses of HAV vaccine achieved similar serologic responses to HIV-uninfected MSM receiving 1 [more] dose," the researchers concluded. "The response rates of these two groups were much higher than that of the HIV-infected MSM who received 1 [more] dose of HAV vaccine."

Investigator affiliations: Taipei City Hospital, Taipei, Taiwan; National Taiwan University Hospital, Taipei, Taiwan.

10/26/10

Reference
Y Tseng, W Liu, C Lu, and others. Comparisons of serologic responses to hepatitis A vaccination between HIV-infected and HIV-uninfected men who have sex with men in the era of highly active antiretroviral therapy. 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010). Boston, September 12-15, 2010. Abstract H-217.