No HIV transmission occurred between couples with discordant HIV statuses who had condomless sex for at least a year while the HIV-positive partner took suppressive antiretroviral therapy (ART) and maintained low viral load, according to a prospective study published online July 12 in JAMA.
"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," write Alison J. Rodger, MD, from the University College London, United Kingdom, and colleagues.
"Based on the number and type of sex acts and the cumulative probability of HIV transmission, more than 100 transmissions would have been expected in the [men who have sex with men (MSM)] group alone if the HIV-positive partner had not been taking ART."
The researchers prospectively tracked 888 sexually active couples from 75 clinical sites across 14 European countries, starting between September 2010 and May 2014. One partner in each couple was HIV-positive, taking suppressive ART, and had an HIV-1 RNA load less than 200 copies/mL. The other partner was HIV-negative, and the couple was not using condoms during anal or vaginal sex.
Among the 61.7% of couples who were heterosexual, 4% of the HIV-negative participants reported having condomless sex with someone other than their regular partner during the study. Of the MSM, comprising 38.3% of the couples, 33% of the HIV-negative participants reported having had condomless sex with someone other than their regular partner. Three percent of the HIV-negative men having sex with men, 2% of the HIV-negative heterosexual men, and 1% of the HIV-negative heterosexual women reported injecting drugs during follow-up.
The researchers note that the couples had been having condomless sex for a median 2 years at baseline and reported having condomless sex during the study a median 37 times annually during a median follow-up of 1.3 years, providing a total of 1238 couple-years for analysis. The HIV-positive partners had a plasma HIV-1 RNA load of less than 50 copies/mL during 94% of the couple's follow-up years. The viral road remained between 50 and 200 copies/mL for the other 6%.
During the study, the heterosexual couples had penetrative sex approximately 18,000 times, and the male couples had anal sex approximately 22,000 times.
None of the HIV-negative partners, however, contracted HIV from their partners enrolled in the study. In one heterosexual couple and 10 male couples, the HIV-negative partner at baseline became HIV-positive, but eight of these individuals reporting having condomless sex with other partners, and none of these infections were phylogenetically linked to their partner's infection.
"Although these results cannot directly provide an answer to the question of whether it is safe for serodifferent couples to practice condomless sex, this study provides informative data (especially for heterosexuals) for couples to base their personal acceptability of risk on," the authors write, noting that the study's follow-up time was relatively short.
This study addresses shortcomings of previous research by including MSM and enrolling participants who mostly had condomless sex with their partners, write Eric S. Daar, MD, and Katya Corado, MD, from the Harbor-University of California, Los Angeles, Medical Center in Torrance, California, in an accompanying editorial. Yet the study's limited power is one weakness of the study, they write.
"A second limitation of the PARTNER study is that the study population represented a select group that may be different than HIV-serodiscordant couples encountered in other settings," Dr Daar and Dr Corado write. "For example, it is possible that couples with stable relationships may be at lower risk for HIV transmission."
The study participants also had a higher-than-average adherence to ART, ranging from 93% to 97%.
More than half the HIV-negative partners said they did not use a condom during sex because they believed the risk for HIV transmission to be very low, as reported by 57% of the heterosexual men, 52% of the heterosexual women, and 63% of the MSM. Another common reason for choosing condomless sex was that it was more enjoyable, as reported by 38% of heterosexual men, 41% of heterosexual women, and 61% of MSM. Only a small percentage of HIV-negative women (15%) said they did not use a condom because they hoped to get pregnant.
"Certainly health care professionals should encourage all HIV-infected individuals to initiate and adhere to ART," write Dr Daar and Dr Corado.
"Clinicians can further emphasize to patients that the use of condoms is an important measure to prevent transmission of [sexually transmitted infections]."
For those who do not use condoms while having sex with an HIV-infected partner, Dr Daar and Dr Corado write, providers can explain that HIV transmission risk appears small if viral suppression remains under control. It is unclear how long HIV-positive partners must remain virologically suppressed to be most protective, but the best data suggest at least 6 months.
"Moreover, clinicians need to be clear that even though the overall risk for HIV transmission may be small, the risk is not zero and the actual number is not known, especially for higher-risk groups such as MSM," Dr Daar and Dr Corado write. "Consequently, for now, clinicians and public health officials must share the data that exist in an honest and understandable way so that serodiscordant couples can be fully informed when individualizing their decision making about sexual practices."
The study was funded by the National Institute for Health Research and the Danish National Research Foundation. Various coauthors reported grants, board member service, or speaking or consultancy fees from one or more of the following: Merck Sharp & Dohme Limited, Gilead, Tibotec, Bristol-Myers Squibb, Gilead, Bionor, ViiV, AbbVie, Abbott, GlaxoSmithKline, Janssen, Pfizer, Roche, and TRB Chemedica. Dr Daar reported receiving research grants from Gilead, Merck, and ViiV and consulting support from Bristol-Myers Squibb, Gilead, Merck, Teva, and ViiV. Dr Corado reported receiving research grant support from ViiV.
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Cite this: Condomless Sex May Be Low Risk for Some HIV-Discordant Couples - Medscape - Jul 14, 2016.