Reuters (02.18.10) - Friday, February 19, 2010
An AIDS vaccine candidate previously reported to have partial
efficacy may have been most useful during a short timeframe,
researchers announced Thursday at the 17th Conference on
Retroviruses and Opportunistic Infections in San Francisco.
The vaccine's temporary protection may have waned after a year
or so, making it more difficult to assess its effects,
reported Dr. Nelson Michael, of the Walter Reed Army Institute
of Research, and colleagues.
"It is very likely that this vaccine only worked for a short
period of time," Michael said. The trial in Thailand showed a
31 percent cut in infection risk over a longer timeframe of
three years. "It is a weak, a modest effect but something that
we can build on."
The vaccine is a combination of Sanofi-Pasteur's ALVAC
canarypox/HIV vaccine and AIDSVAX, made by VaxGen and now
owned by the nonprofit Global Solutions for Infectious
Though the trial enrolled 16,000 volunteers, they were not
individuals at particularly high risk of HIV infection,
Michael said. Dr. Anthony Fauci, director of the National
Institute of Allergy and Infectious Diseases, and Michael will
work together to design a trial in Asia or Africa to better
determine whether the vaccine can be useful.
"Is [short-term protection] ideal? No," said Michael. "But it
is true there are vaccines like the flu vaccine where you have
to get them every year."
Researchers next will examine the blood of trial participants
to look for clues as to why the vaccine worked. Labs around
the world will be searching for correlates of efficacy, such
as measurements of antibodies that indicate some immune system
response, Michael said. Those results could take roughly a