HAART Improves Hepatitis B Vaccine Response Regardless of CD4 Count

By Liz Highleyman

Due to overlapping transmission routes, many people with HIV are also exposed to hepatitis B virus (HBV). An effective hepatitis B vaccine is available, and is recommended for all HIV positive individuals. But past studies indicate that it does not work as well for HIV positive people with advanced immune deficiency and low CD4 cell counts.

As reported at the 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008) last week in Washington, DC, a team of U.S. military medical researchers conducted a study to assess the impact of HAART on response to hepatitis B vaccination in HIV-infected individuals.

The investigators analyzed factors associated with developing a protective response to HBV vaccination among 626 participants in the Tri-Service AIDS Clinical Consortium HIV Natural History Study (mostly active duty personnel and their dependents, but also some veterans).

Patients without prior vaccination who received at least 1 dose of an HBV vaccine after HIV infection were included. The standard HBV vaccine series consists of 3 doses administered over 6 months; a combined hepatitis A and B vaccine is also available.

The median age was about 30 years and about 45% each were white and African-American. At the time of vaccination, most participants had well preserved immune function, with a median CD4 count of 490 cells/mm3.

Hepatitis B surface antibody (HBsAb) results 3-9 months after the last vaccine dose were used to classify recipients as responders (HBsAb > 10 IU/L) or non-responders (HBsAb <10 IU/L).

Results

• Overall, about 44% of vaccinated individuals were classified as responders (compared with about 90% for HIV negative people).

• In a multivariate analysis, men had a lower likelihood of response compared with women (odds ratio [OR] 0.54).

• Individuals who received at least 3 vaccine doses were significantly more likely to respond than those who received 2 or fewer doses (OR 2.07).

• Among patients on HAART, those with a CD4 count > 350 cells/mm3 and those with 350 cells/mm3 had a similar likelihood of mounting a good response.

• Individuals not on HAART at the time of vaccination, however, had a significantly lower likelihood of developing a vaccine response, regardless of CD4 count (OR 0.25 for < 350 cells/mm3; OR 0.53 for > 350 cells/mm3).

Based on these findings, the investigators concluded that, "Receipt of HAART at the time of initial hepatitis B immunization significantly increased the probability of developing a protective hepatitis B vaccine response in patients with HIV, even those with CD4 counts > 350, providing additional evidence of benefits from HAART in those with higher CD4 counts."

This study adds to the growing body of data suggesting that HIV positive people may benefit from antiretroviral therapy before their CD4 count falls below 350 cells/mm3, the threshold in current U.S. and European guidelines.

San Antonio Military Med. Ctr., San Antonio, TX; Infectious Disease Clin. Res. Program, Bethesda, MD; Univ. of Minnesota, Minneapolis, MN; Natl. Navy Med. Ctr., Bethesda, MD; Walter Reed Army Med. Ctr., Washington, DC; Naval Med. Ctr., San Diego, CA; Naval Med. Ctr., Portsmouth, VA; Walter Reed Army Inst. of Res., Silver Spring, MD.

11/07/08

Reference
M Landrum, K Hullsiek, A Ganesan, and others. Highly Active Antiretroviral Therapy Improves Hepatitis B Vaccine Response Regardless of CD4 Count. 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008). Washington, DC. October 25-28, 2008. Abstract H-2314.