Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. Journal of the American Medical Association (JAMA)
Rodger et al. on behalf of the PARTNER study group followed serodifferent partnerships in which the HIV-positive partner took antiretroviral therapy (ART) with a plasma HIV-1 RNA load less than 200 copies/ml to study the risk of HIV transmission through anal and vaginal sex in the absence of condom use. Among 1’166 enrolled couples, 548 heterosexual and 340 men who have sex with men provided 1’238 eligible couple-years.
During a median follow-up of 1.3 years per couple, 11 HIV-negative partners became HIV-positive. However, there were no phylogenetically linked cases of within-couple HIV transmission, giving a rate of within-couple HIV transmission of zero, with an upper 95% confidence limit of 0.30/100 couple-years of follow-up. Of note, acquisition of a sexually transmitted infection was not associated with risk of HIV-1 transmission within the couples under study.
In conclusion, this study provides the first estimate of HIV transmission risk through condomless anal sex in which the HIV-positive partner is taking ART with suppressed plasma HIV viral load. However, 95% confidence limits suggest that with eligible couple-years accrued so far, appreciable levels of risk cannot be excluded, particularly for anal sex and when considered from the perspective of a cumulative risk over several years. Therefore, additional longer-term follow-up is needed to provide more precise estimates of risk.