March 2016

Many people get their health news from the media, which may relay information that is incorrect or, more often, incomplete. Anyone who checks the news or social media, or any media for that matter, has learned about Charlie Sheen—HIV-infected but with undetectable levels of virus in his serum—and how he had condom-less sex with a couple of partners. However, those reports failed to educate readers and viewers about the risks and protections for HIV transmission.

The National Institutes of Health recently reported on the very low risk of HIV transmission from someone receiving antiretroviral therapy. Good news, undoubtedly—a win-win both for treatment of an infected individual and for prevention of transmission to an uninfected partners. But how should a HIV-uninfected partner be counseled regarding risk if she or he may have a treated partner with undetectable HIV-load?

Beginning in 2005, NIH enrolled 1,763 heterosexual discordant couples in Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, the United States, and Zimbabwe. One partner was HIV-infected and the other HIV-uninfected. The HIV-infected partners were randomly assigned to either start antiretroviral therapy (ART) right away (early) or to delay until they developed symptoms. Subjects in both groups were counseled in safer sex practices and to use condoms, which were provided at no cost. Although the randomized control study was stopped in 2011 to offer immediate ART treatment to all HIV-infected persons (because treatment was so effective in preventing transmission),[1] the study was not complete until 2015. In the final analysis, NIH reported that early ART treatment reduced HIV transmission by 93%.[2] [3] Among the HIV-infected study participants who delayed taking ART, 43 of their partners became newly infected. But among the study participants who started ART early, only 8 cases of transmission occurred, with half most likely occurring before treatment had fully suppressed HIV replication. The other cases were thought to occur because the treatment was not taken as prescribed or because a partner’s HIV strain was resistant to the treatment.

Terrific news. ART treatment offers even better protection than does condom use alone with HIV-infected partners. But that is not the entire story, and uninfected partners need to be fully informed. First, undetectable levels of virus do not equate with the absence of virus. The only persons in whom HIV is absent are those who are not infected with the virus to begin with. So what undetectable means is that when the serum is checked, the virus resides at less than 40-75 copies of the virus per ml of blood. It indicates the level of virus load at the time of testing only, not during the time between tests, so it is possible the viral load may increase without the infected person knowing it. ‘Undetectable’ also does not mean that the virus is absent in other body fluids such as semen or vaginal discharges. Further it is thought that co-infection with another STD may boost the HIV load in genital fluids. (See https://www.aids.gov/hiv-aids-basics/just-diagnosed-with-hiv-aids/understand-your-test-results/viral-load/)

What an undetectable level does indicate is that the HIV-infected individuals have been taking ART as prescribed, are healthy, and have good immune system response. With fewer copies of HIV in their bodies, they present fewer opportunities to transmit the virus to their uninfected partners. And in regard to the participants in the NIH study of heterosexual discordant couples, the 93% reduction in transmission risk was seen only among those couples in which the HIV-infected partner had been consistently taking ART as prescribed and also maintained a consistently undetectable HIV load.

What would an informed uninfected partner need to know?

1. Use condoms. Condom use further reduces your risk of HIV, even if your HIV-infected partner is taking ART and has an undetectable viral load.¹
2. Are you, as an uninfected partner, taking or planning to take pre-exposure prophylaxis (PrEP), which also reduces risk, though not to zero. (Mr. Sheen said two women, with whom he had condom-less sex, had opted to take PrEP.[4])
3. Is your HIV-infected partner taking ART? Consistently and as prescribed?
4. When was your HIV-infected partner’s last test of viral load?
5. Does your HIV-infected partner possibly have another STD, too?

For individually tailored information, consult the HIV Risk Reduction Tool developed by the Centers for Disease Control and Prevention: https://wwwn.cdc.gov/hivrisk/

For another potential win-win scenario, a new randomized study (HPTN 074) has begun enrollment in Indonesia, Ukraine, and Vietnam to test integrated treatment and prevention for people who inject drugs. Index participants have HIV viral loads greater than 1,000 copies/mL at screening, and their partners will be uninfected.

—Deborah Kowal, MA, PA, Executive editor of Contraceptive Technology

—Ward Cates, Jr., Distinguished Scientist and President Emeritus, FHI 360, Durham North Carolina