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Risk for HIV acquisition with HIV vaccine confirmed on follow-up
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The risk for HIV acquisition associated with adenovirus serotype 5–vectored HIV vaccine, first identified during an interim analysis in the Step Study, was confirmed in extended follow-up, recent data suggest.
The Step Study tested the HIV vaccine among high-risk, uninfected men who have sex with men and high-risk heterosexual men and women. When the trial was halted after the interim analysis, the participants were encouraged to remain on follow-up for 4 years after first vaccination or until Dec. 31, 2009. The researchers then analyzed the risk for HIV acquisition among the participants.
The follow-up study included 1,836 participants, most of whom received all three vaccinations. During the follow-up period, there were 172 infections. The HIV incidence during the entire follow-up time was 3.3 per 100 person-years. The incidence after the first 18 months of enrollment was 3.06 per 100 person-years.
There was a higher risk for HIV infection among those who received the vaccine vs. those who did not (HR=1.44; 95% CI, 1.05-1.97). The greatest HR was seen in men who were uncircumcised and adenovirus serotype 5–seropositive, in which the risk was more than four times greater than in those who received placebo. This risk waned since vaccination.
“Although ongoing work has uncovered some potential correlates of risk of infection in the RV144 Trial, our understanding of the correlates of vaccine protection against HIV infection remains far from complete,” the researchers wrote. “Ongoing research using specimens from Step and RV144 study participants should inform future trials by delineating vaccine-induced responses that are irrelevant or harmful from those that protect.”
References:
Duerr A. J Infect Dis. 2012;206:258-266.
Disclosures:
Some of the researchers report financial relationships with Merck.