Hepatitis A vaccine provides affordable protection in HIV-positive individuals

The use of an inactivated hepatitis A (HepA) vaccine provides affordable protection against HAV infection, which may be of particular importance in those who are HIV-infected. One of the inactivated HepA vaccines, HAVRIX, is highly immunogenic in non HIV-infected adults, resulting in seroconversion in up to 90% to 94% and 100% of persons after the first and second doses, respectively, of vaccine.

However, antibody responses to HepA vaccine are lessened in patients with HIV infection. The researchers examined whether two doses of vaccine, administered six months apart, adversely affected CD4 cell counts, plasma HIV RNA levels, or the clinical course of HIV-infection.

A total of 270 adults were screened, 133 of whom were HAV seronegative and enroled in the study (mean age, 38 years; range, 22-65 years). Of the 68 subjects (51.1%) who were randomly assigned to receive HepA vaccine, 48 (70.6%) completed the nine-month study. Of the 65 (48.9%) who received placebo, 51 (78.5%) completed the study. Sixty-two patients (91%) in the vaccine group were receiving antiretroviral therapy at the time of entry to the study, compared with 60 (92%) in the placebo group.

The overall frequency of seroconversion among subjects receiving vaccine was 49% at month seven and 52% at month nine. Among patients with baseline CD4 cell counts of 200-499 or greater than or equal to 500 cells/mm3, seroconversion was observed in 53% and 73% at month seven and in 69% and 67% at month nine, respectively. After the first dose of vaccine, seroconversion at month six was observed in only four (13%) of 31 subjects with CD4 cell counts greater than or equal to 200 cells/mm“ and in no subjects with CD4 cell counts less than 200 cells/mm“.

The authors found no transient increases in plasma HIV loads after administration of HepA vaccine on HIV RNA levels. Increases in CD4 cell counts and decreases in HIV loads were observed in both subject groups throughout the study. Furthermore, the study demonstrated that the frequency of seroconversion and the magnitude of the resulting antibody titer varied significantly, depending on the initial CD4 cell count.

The authors conclude: “HepA was well tolerated and had no apparent effect on the course of HIV infection or plasma HIV RNA levels. Approximately two-thirds of our patients responded to two doses of vaccine administered six months apart. Compared with uninfected persons and with the results of other studies of HIV-infected persons, this relatively lower response rate was unexpected and remains unexplained…. Clinicians may wish to counsel patients that vaccination may not provide uniform protection against HAV. Whether vaccine response can be improved by the use of adjuvants or a third dose of vaccine or by delaying vaccination until there is evidence of improvement in the immune system in response to more highly active antiretroviral therapy, deserves further study.”