Released 25 September, 2009: Yesterday
it was reported that an HIV vaccine regimen led to a marginal but
statistically significant degree of protection against acquisition of
HIV infection. The only information provided by the trial sponsors in
their press releases is that 74 out of 8,198 volunteers who received
placebo immunizations became infected with HIV compared to 51 out of
8,197 volunteers who received a combination of two vaccines, ALVAC
vCP1521 and AIDSVAX B/E. Seven of the original 16,402 volunteers were
excluded from the efficacy analyses after it was found that they were
HIV-infected at the time of receiving their first vaccination. The
result equates to a protective efficacy of a little over 31%, but with
a very wide “95% confidence interval” spanning from 1.1% to 52.1% (a
confidence interval is a statistical method for conveying the degree of
uncertainty associated with a result; if the lower bound of the
confidence interval is less than 1, the result is not statistically
significant). The vaccines had no effect on post-infection viral load
levels among the recipients who became infected.
These results are very welcome given the many unwelcome surprises
that have assailed the HIV vaccine field over the past few years.
However, based on the limited amount of information that has been
released, it appears that the statistical significance hangs on very
few cases of HIV infection. TAG urges caution in interpreting the
findings until more detailed information is available. In light of the
potential importance of the results to efforts to prevent HIV
infection, and the level of public interest, TAG is disappointed that
the trial sponsors did not include more data with their news releases.
TAG’s Position on the Trial
When
the trial was launched, TAG stated our concern that the lack of data on
the efficacy of ALVAC alone would preclude an understanding of whether
the inclusion of AIDSVAX added to, or subtracted from, any potential
benefit (Science 305;5681:180). Now that there is an indication of
possible efficacy, this issue looms large. Many people worked
diligently and in good faith on this trial and it is disheartening that
such a huge undertaking is still unable to provide definitive answers
as to the efficacy of the candidates studied. Instead, if the results
hold up to scrutiny, more trials will be required to try and understand
what happened.
TAG will provide additional information and commentary on the trial results when the details become available.
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About
TAG: Treatment Action Group is an independent AIDS research and policy
think tank fighting for better treatment, a vaccine, and a cure for
AIDS. TAG works to ensure that all people with HIV receive life saving
treatment, care, and information. We are science-based treatment
activists working to expand and accelerate vital research and effective
community engagement with research and policy institutions. TAG
catalyzes open collective action by all affected communities,
scientists, and policymakers to end AIDS.