— Christine M. Kukka, Project Manager, HBV Advocate
South African researchers who are working on
developing an effective vaccine against HIV infection, examined other
factors that could render vaccines ineffective and found that obesity
may hinder the performance of the hepatitis B vaccine.
According to their report in the December issue of the journal PLoS One,
researchers conducted a follow-up study of women who had been recently
immunized against hepatitis B. None of the women were HIV-infected.
They found that obese women with
a high body mass index (BMI) often failed to develop adequate
hepatitis B antibodies after immunization, which are needed to protect
them against infection.
Obese individuals (BMI index at
or greater than 30kg/m(2)) were significantly more likely to be vaccine
non-responders following two HBV vaccine doses, they reported.
"There was no observed
association between vaccine responses and age, method of contraception
or time from vaccination to antibody measurement," they wrote,
suggesting that obesity may limit the vaccine's effectiveness.
An unrelated article in the December issue of the journal Vaccine
found that old age does not decrease the effectiveness of the
hepatitis B vaccine in the elderly. U.S. Centers for Disease Control
and Prevention researchers reported that 22 out of 27 residents in an
assisted living facility responded well to the vaccine and generated
adequate protective antibodies after immunization.
The residents had been
vaccinated against both hepatitis A and B following an outbreak of
hepatitis B resulting from improperly re-used medical devices. Of the
27 residents who were screened for hepatitis B surface antibodies after
their three-dose immunizations, 22 (81%) achieved protection. The
vaccine protected even elderly residents age 75 and older.
"Adult vaccine recipients of all
ages, even those over 60 years of age, demonstrated a robust capacity
for achieving hepatitis B seroprotection in response to the combined
hepatitis A/B vaccine," they wrote. "The role for vaccination in
interrupting HBV transmission during an outbreak remains unclear, but
concerns about age-related response to hepatitis vaccine may be
insufficient to justify foregoing vaccination of susceptible residents
of assisted living facilities."
Labels: age, obesity, vaccine, vaccine efficacy