Improves Hepatitis B Vaccine Response Regardless of CD4 Count
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.
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.
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).
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.
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).
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).
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."
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.
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,
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