Prevention for Persons With HIV


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Treatment as Prevention

People with HIV should take medicine to treat HIV as soon as possible. HIV medicine is called antiretroviral therapy, or ART. If taken as prescribed, HIV medicine reduces the amount of HIV in the body (viral load) to a very low level, which keeps the immune system working and prevents illness. This is called viral suppression—defined as having less than 200 copies of HIV per milliliter of blood. HIV medicine can even make the viral load so low that a test can’t detect it. This is called an undetectable viral load.

Getting and keeping an undetectable viral load is the best thing people with HIV can do to stay healthy. Another benefit of reducing the amount of virus in the body is that it helps prevent transmission to others through sex or syringe sharing, and from mother to child during pregnancy, birth, and breastfeeding. This is sometimes referred to as treatment as prevention. There is strong evidence about treatment as prevention for some of the ways HIV can be transmitted, but more research is needed for other ways.

In 2011, the interim results of the HPTN052 clinical trial2 demonstrated a 96% reduction in HIV transmission risk among heterosexual mixed-status (also referred to as HIV-discordant) couples where the HIV-positive partner started antiretroviral therapy (ART) immediately versus those delaying ART initiation. The final results published in 2016 reported that there had been no HIV transmissions within these couples when the HIV-positive partner had a suppressed viral load (defined as having a viral load of less than 400 copies of HIV RNA per milliliter).3 Genetically linked HIV infections were observed between sexual partners in 8 couples; however, all of these transmissions occurred while the HIV-positive partner was not virally suppressed. In other words, linked HIV transmissions occurred only when:

  • The HIV-positive partner had started ART but before the HIV-positive partner had achieved and maintained viral suppression, or
  • The HIV-positive partner had achieved viral suppression but the ART regimen later failed or the partner had stopped taking their medication.

Three recent studies, PARTNER, Opposites Attract, and PARTNER2 (an extension of PARTNER focusing on HIV-discordant MSM couples), report similar results. None of these studies observed any genetically linked infections while the HIV-positive partner was virally suppressed and the couples were engaging in condomless sex and not using pre-exposure prophylaxis (PrEP).4-6 In these studies, viral suppression was defined as less than 200 copies of HIV RNA per milliliter of blood; most HIV-positive participants in the PARTNER study had less than 50 copies of HIV RNA per milliliter of blood.3 The three studies included over 500 HIV-discordant heterosexual couples, with about half having a male HIV-infected partner (PARTNER), and more than 1,100 HIV-discordant MSM couples (PARTNER2; Opposites Attract) from 14 European countries, Australia, Brazil, and Thailand. Combined, these couples engaged in over 125,000 sex acts without a condom or PrEP over more than 2,600 couple-years of observation.

The studies reported transmission risk estimates and their corresponding 95% confidence intervals as:

  • PARTNER study:28
    • For any sex among heterosexual and male-male couples: 0.00 (0.00 – 0.30) per 100 couple-years
    • For anal sex among male-male couples: 0.00 (0.00 – 0.89) per 100 couple-years
  • Opposites Attract study:5
    • For anal sex among male-male couples: 0.00 (0.00 – 1.59) per 100 couple-years
  • PARTNER2 study (which includes data from PARTNER):6
    • For anal sex among male-male couples: 0.00 (0.00 – 0.24) per 100 couple-years

Together, the data from the PARTNER2 and Opposites Attract studies produce a combined transmission risk estimate for condomless and PrEP-less anal sex among MSM couples of 0.00 (0.00 – 0.21) per 100 couple-years, with the upper bound equal to a 0.21% annual risk (unpublished data). Pooling data from all three studies produces a combined transmission risk estimate for condomless sex among heterosexual or MSM couples of 0.00 (0.00 – 0.14) per 100 couple-years, with the upper bound indicating a 0.14% annual risk (unpublished data). These data provide conclusive evidence of the power of viral suppression in preventing HIV transmission. Although statistically a non-zero risk estimate can never be completely ruled out in a mathematical sense, despite the number of observations, the data tell us that the best estimate for the transmission risk is zero and that future HIV transmissions are not expected when persons with HIV remain virally suppressed.

While treatment as prevention is a highly effective prevention strategy, its success depends on achieving and maintaining an undetectable viral load. If the patient’s viral load increases, so does their risk of transmitting HIV to their HIV-negative partners through sex. For patients who rely on treatment and viral suppression as a prevention strategy, it is not known if viral load testing should be conducted more frequently than currently recommended for treatment.

People with HIV who use or want to use ART as their primary means of prevention may benefit from additional prevention methods if either partner desires added security for HIV protection or is concerned about STDs (e.g., PrEP and/or condoms). Using multiple HIV prevention methods is especially important if the person with HIV has trouble with adherence or has not achieved or maintained viral suppression. We describe other ways to prevent HIV transmission below, including PrEP, PEP and condoms.

For more information, visit the TasP webpage.

Conversations about Treatment as Prevention for Sexual Transmission

illustration of doctor talking to patient

Talking to patients with HIV about treatment as prevention and the benefits of viral suppression is one of the best things health care providers can do for their overall health and to stop HIV transmission.

At every office visit, providers should aim to engage their patients in brief conversations about the prevention steps they are taking. These conversations can help providers become more familiar with each patient, including their adherence and transmission risk. In addition, these conversations can normalize discussions about factors that may affect a patient’s health, such as sex, substance use, and mental health disorders.

It may be helpful for providers to share information with patients about the research on treatment as prevention then ask them open-ended questions to start the conversation. Here are some examples:

  • “Studies have followed mixed-HIV-status couples who engaged in thousands of unprotected sex acts while the partner with HIV was suppressed on ART. Not a single HIV-negative person got HIV from their sexual partner with an undetectable viral load. What does this information mean to you?”
  • “You have to both achieve and then maintain an undetectable viral load to maximally reduce any risk of sexually transmitting HIV – how do you feel about that?”
  • “Your viral load continues to be undetectable, which is great! Can you tell me the methods you are using to prevent other STDs?”

Once the conversation has started, health care providers can use the information their patients share with them to identify barriers those patients may have to adhering to ART and regular, ongoing care that may make it difficult for them to achieve and maintain viral suppression.

Pre-Exposure Prophylaxis (PrEP) and Post-Exposure Prophylaxis (PEP)

To prevent HIV acquisition, both PrEP and PEP may be appropriate for sex and injection drug partners of people with HIV. Learn more about PrEP and PEP.

Multiple Prevention Options

With multiple HIV prevention options available, everyone with or without HIV who has sex or injects drugs should learn about all their options and use the prevention strategies that work for them. Using multiple prevention methods can provide added protective benefits, as well as added peace of mind for both partners.

Note for Conception

Mixed-HIV-status couples who are planning to conceive may consider the following:

  • Treatment as prevention
  • Limiting condomless sex to the time of ovulation
  • Using PrEP
  • Semen processing prior to insemination or fertilization, especially when fertility treatment is needed

Related Resources

  1. Kitahata MM, Gange SJ, Abraham AG, et al. Effect of early versus deferred antiretroviral therapy for HIV on survival. N Engl J Med. Apr 30 2009;360(18):1815-1826. PubMed abstractexternal icon.
  2. Cohen MS, Chen YQ, McCauley M, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med. Aug 11 2011;365(6):493-505. PubMed abstractexternal iconexternal icon.
  3. Cohen MS, Chen YQ, McCauley M, et al. Antiretroviral therapy for the prevention of HIV-1 transmission. N Engl J Med. 2016;375:830-9. PubMed abstractexternal iconexternal icon.
  4. Rodger AJ, Cambiano V, Bruun T, et al. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. JAMA 2016;316(2):171-81. PubMed abstractexternal iconexternal icon.
  5. Bavinton B, Grinsztejh B, Phanuphak N, et al. HIV treatment prevents HIV transmission in male serodiscordant couples in Australia, Thailand and Brazil. Presented at the 9th IAS Conference on HIV Science (IAS 2017), Paris, France; July 25, 2017.
  6. CDC. Evidence of HIV Treatment and Viral Suppression in Preventing the Sexual Transmission of HIV.