HIV

Q: If I am on HIV medications and my viral load is undetectable (meaning that the virus isn't showing up on blood tests), can I still pass the virus to another person through sex?

Our current HIV medication regimens (antiretroviral therapy, or ART) are extremely effective at preventing HIV transmission to a sex partner if the HIV viral load is undetectable. The following three research studies have focused on this question.

A large international study looked at couples (largely heterosexual) in which one partner was HIV positive and the other was HIV negative (we call these serodifferent couples). The study found that if the person with HIV took ART to suppress their viral loads, their risk of infecting their partners was enormously reduced, by 93% overall, over about 5 years. And, if the person with HIV was consistently on HIV medications, with an undetectable HIV viral load, there were no partner infections. It is important to note that the couples in this study were encouraged to use condoms.

A smaller study looked at both male-female and male-male serodifferent couples who did not use condoms (and did not plan to use them). All of the people with HIV in the study were on ART and had undetectable HIV viral loads. After more than a year, none of the HIV-negative partners had been infected by their partner. As a reminder, if someone does have a detectable HIV viral load it is very important to use condoms.

The third study examined male-male serodifferent couples. Again, all of the people with HIV were on ART and had undetectable HIV viral loads. During the study, there were more than 12,000 episodes of anal receptive sex (which confer the highest risk of HIV transmission) in which there was no use of condoms or PrEP. There were no HIV transmissions between the positive men on ART and their HIV-negative partners.

The results of these studies show that if a person with HIV is on ART with a completely suppressed HIV viral load, the risk of infecting an HIV-negative sex partner is exceedingly low. The CDC reviewed these data and stated that, "People who take ART daily as prescribed and achieve and maintain an undetectable viral load have effectively no risk of sexually transmitting the virus to an HIV-negative partner."

This is extremely reassuring for everyone who takes ART every day and whose viral load stays undetectable. As you think about yourself and your partner(s), here are some things to consider:

• The risk of HIV transmission will increase substantially if someone's HIV viral load goes up, for example if they miss medication doses or stop taking their ART.
• An HIV-negative person will not be protected from being infected by any other HIV-positive partners who are not taking ART.
• We have very few data on how effective ART is in preventing HIV transmission via sharing injection drug equipment.
• ART does not prevent pregnancy — use other strategies (such as condoms) as needed.
• ART does not prevent sexually transmitted diseases (STDs) — it is very important to use condoms to prevent other STDs such as gonorrhea, chlamydia, syphilis, hepatitis B and hepatitis C.

It is important to ask your health care provider for advice that is targeted to you as an individual, and to your partner, about the risks of passing HIV. And of course, it is really important to have frank and open conversations about HIV transmission with your HIV-negative partner(s), so you and they can make informed decisions about sexual health.