1. Can a person living with HIV on treatment with an undetectable viral load transmit HIV through sex?
No. A person living with HIV on antiretroviral therapy (ART) who has an undetectable viral load (under 200 copies/mL) cannot transmit HIV through sex. For information about HIV transmission through perinatal transmission (from mother to child during pregnancy, labor and delivery, or breastfeeding) or injection drug use, please see questions 15 and 19 below.National Institutes of Health: "HIV Undetectable=Untransmittable (U=U), or Treatment as Prevention" World Health Organization: "Viral suppression for HIV treatment success and prevention of sexual transmission of HIV"
2. What is an “undetectable viral load” and what is “viral load suppression”?
Viral load refers to the amount of HIV in a blood sample of a person living with HIV. Generally, the higher the viral load, the more likely you are to transmit HIV. Both “undetectable” and “viral load suppression” are extremely low measurements of HIV that are basically the same. Often, they are both used to describe the same important result of taking ART as prescribed by a healthcare provider: extremely low measurements of HIV in a blood sample.
– Undetectable viral load: ART can reduce a person’s viral load to the point where it is so low it can’t be measured by laboratory tests. This is usually under 40 copies/mL but the exact definition of “undetectable” varies by test/region. This is called ‘having an ‘undetectable viral load,’ which prevents the sexual transmission of HIV while simultaneously improving the health of a person living with HIV. It does not fully clear the virus from the body or cure someone of HIV. Excellence adherence, or taking ART as prescribed by a healthcare provider, is important to maintain an undetectable viral load.
– Viral load suppression: When ART suppresses a person’s viral load to less than 200 copies/mL, this is often called being “virally suppressed.” Being virally suppressed prevents the sexual transmission of HIV and at the same time improves the health of a person living with HIV. Studies show that when a person is virally suppressed they cannot transmit HIV to sexual partners. Excellent adherence, or taking ART as prescribed by a healthcare provider, is important to maintain viral suppression.
For the purposes of the U=U campaign, the terms “undetectable” and “virally suppressed” mean the same thing. Because the exact numbers for “undetectable” and “virally suppressed” may continue to change, it is important to remember that any test result that shows a number less than 200 copies/ml indicates that HIV is not transmittable. A person living with HIV cannot transmit HIV through sex when their viral load is less than 200 copies/ml.NAM aidsmap: "What does undetectable mean?"
3. What is the evidence?
The conclusion is based on the overwhelming force of real world and research evidence including the Swiss Statement and the HPTN 052, PARTNER, PARTNER 2, and Opposites Attract studies. For example, in HPTN 052 there were ZERO transmissions between 1,763 mixed-status couples when the HIV positive partners were on ART with undetectable viral loads. In the PARTNER study, there were ZERO transmissions out of 58,000 condomless sex acts between people with HIV on ART who had undetectable viral loads and their HIV negative partners. In PARTNER 2, which was the extension of PARTNER and studied men who have sex with men, there were ZERO transmissions out of 77,000 condomless sex acts between people living with HIV on ART with undetectable viral loads and their HIV negative partners. In the Opposites Attract study, there were ZERO transmissions out of 17,000 condomless sex acts between an undetectable male with HIV on ART and their HIV negative, male partner. Since the development of combination therapy, there have been no confirmed reports of anyone with an undetectable viral load sexually transmitting HIV.HPTN 052 PARTNER 1 PARTNER 2 Opposites Attract Swiss Statement
4. Is the risk zero?
In real-world terms, yes, the risk is zero. It’s not helpful to focus on the theoretical risks because it is never possible to prove zero risk in science. Through statistical analysis, the estimated risk will keep getting closer and closer to zero. Researchers agree we can confidently say that a person with HIV on ART with an undetectable viral load cannot transmit HIV to their sexual partners. When someone is virally suppressed, they are not infectious and the risk of transmitting HIV is scientifically equivalent to zero.NAM aidsmap: "Zero transmissions mean zero risk" World Health Organization (WHO): Viral suppression for HIV treatment success and prevention of sexual transmission of HIV Medscape: "Undetectable HIV Is Untransmittable and the 'Risk Is Zero'" CDC Effectiveness Estimates: Viral Suppression "100% effective" at preventing HIV transmission [imstilljosh]: "Fauci: From A Practical Standpoint The Risk Is ZERO" Dr. Alison Rodger: "It is very, very clear that the risk is zero." British HIV Association: "BHIVA Encourages Universal promotion of Undetectable=Untransmittable (U=U)"
5. What does ‘Treatment as Prevention’ mean?
Treatment as prevention (TasP) refers to any HIV prevention method that uses ART to decrease the risk of HIV transmission to a sexual or needle-sharing partner, or through vertical transmission (pregnancy, childbirth, and breast/chestfeeding). ART reduces the HIV viral load in the blood, semen, vaginal fluid, breastmilk, and rectal fluid to very low levels, and as a result reduces HIV transmission. TasP is the foundation for U=U. TasP does not indicate the amount of reduction in the risk or the level of viral load required to prevent transmission. U=U builds upon TasP by indicating the the level at which there is no risk of transmitting HIV sexually. Dr. Julio Montaner pioneered the concept of TasP in 2006.Avert: "Treatment as Prevention (TASP) for HIV"
6. Does everyone who starts HIV treatment become and remain undetectable?
Nearly everyone who starts ART finds a drug regimen that works within six months. About one out of six people will need additional time to find the right treatment due to possible side effects and adherence issues. Continuing treatment and getting regular viral load monitoring are important to maintain an undetectable viral load.NIAID: "10 Things to Know About Viral Suppression" JIAS: "Rate of viral load failure over time in people on ART in the UK"
7. Are there any side effects to being on HIV medicines?
HIV medicines can cause side effects for some people. Most are manageable. Fortunately, there are numerous HIV medicines available today that people can take without serious side effects. If you do experience any side effects it is important to discuss these with your healthcare provider.HIV.gov: "Side Effects of HIV Medicines"
8. Do viral “blips” increase the chance of transmission?
Small transient increases in viral load (between 50 and 1000 copies) known as ‘blips’ sometimes occur on effective ART when people are taking their medication as prescribed by a healthcare provider. After a blip, viral load typically returns to undetectable levels without any change in treatment. Viral blips have not been shown to increase the transmission of HIV. Unless the viral blips start to increase in frequency, they do not mean treatment isn’t working and are normally not of concern to healthcare providers. For more information about viral load testing and frequency, please see question 11.
9. Does having a sexually transmitted infection (STI) affect the chance of HIV transmission?
Having an STI is not significant to HIV transmission when the partner with HIV has an undetectable viral load. An STI (in either the HIV-positive or HIV-negative partner) in the presence of a detectable viral load may increase the risk of HIV transmission. According to the CDC, consistent and correct latex condom use is highly effective in preventing STIs and associated conditions, and sexual transmission of HIV.
STIs were present during the PARTNER studies, and U=U still applied. For more information on the PARTNER study, see question 3 above.JIAS: "Sexually transmitted infections and HIV RNA levels in blood and anogenital compartments among Thai men who have sex with men before and after antiretroviral therapy: implication for Treatment as Prevention programme" CDC: Condom Effectiveness
10. Why do some people have detectable viral loads?
Access to adequate healthcare, treatment, and viral load testing are serious barriers in many parts of the world. Some people who have access to treatment may choose not to be treated or may not be ready to start. Others start treatment but have challenges with taking their medication regularly for a variety of reasons such as stigma, mental health challenges, substance abuse, unstable housing, difficulty paying for medications, hostile environments, drug resistance, and/or intolerable side effects. Additionally, second and third line ART options may not be available to all.
Some people with low but detectable viral loads also cannot transmit HIV. For instance, someone who is virally suppressed (under 200 copies/ml) and still detectable (above approximately 40 copies/ml depending on the test) cannot transmit HIV. For people living with HIV who are not virally suppressed or undetectable, there are highly effective options including condoms, and in some parts of the world, PrEP, to prevent HIV. Condoms and PrEP can be used individually or in combination to prevent HIV. Everyone living with HIV regardless of their viral load status has the right to full and healthy social, sexual, and reproductive lives. U=U is a call to action to ensure access to treatment, care, and services for all people living with HIV.POZ Magazine: "Viral Load Does Not Equal Value" HIV.gov: "Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living with HIV"
11. How often should viral load testing be done?
According to the United States Health and Human Services (HHS) clinical HIV guidelines, “patients on a stable, suppressive ARV regimen, viral load should be repeated every 3 to 4 months or as clinically indicated to confirm continuous viral suppression. Clinicians may extend the interval to 6 months for adherent patients whose viral load has been suppressed for more than 2 years and whose clinical and immunologic status is stable.” In high-resource countries, providers are increasingly conducting viral load testing on an annual (once every 12 months) basis.
The World Health Organization (WHO) guidelines, most often followed in low and middle income countries, however, note on page 148, “Routine viral load monitoring for early detection of treatment failure: obtain and review result by 6 months after ART initiation, 12 months after ART initiation and yearly thereafter.”United States HHS: "Plasma HIV-1 RNA (Viral Load) and CD4 Count Monitoring" World Health Organization (WHO) Consolidated guidelines on HIV prevention, testing, treatment, service delivery and monitoring
12. What if there is detectable HIV in semen, vaginal or rectal fluids but not in the blood?
Scientists have found that HIV treatment that leads to an undetectable viral load in the blood also normally leads to an undetectable viral load in semen, vaginal, and rectal fluids.Occasionally enough HIV genetic material is found in semen, vaginal and rectal fluids to register as a detectable viral load in tests. But this is usually both very low and transient, and may not indicate the presence of entire, replicating virus. Such viral load results have not been found to increase transmission risk. Further, studies show that HIV RNA and DNA are most common soon after starting HIV treatment and are hardly seen after a year or more of an undetectable viral load in the blood.NIAID: "HIV Treatment, the Viral Reservoir, and HIV DNA"
13. What does U=U mean for me if I have HIV?
It means that if you are undetectable and stay on HIV treatment, you are likely to be much healthier than if you were not on treatment and also that you no longer need to be afraid of transmitting HIV to others during sex. As stated in the NAM aidsmap resource “Undetectable viral load and transmission – information for people with HIV”, “If you have sexual partners who are not living with HIV, explaining U=U to them is likely to be mutually beneficial. If you had previously relied on other means of preventing HIV transmission (such as using condoms or PrEP), you may jointly decide that these methods are no longer necessary because of U=U.” It is important to remember that while an undetectable viral load will protect your partners from your HIV, it does not protect them or you from other sexually transmitted infections (STIs) or prevent unwanted pregnancy. Condoms are highly effective at preventing STIs. Condoms and other birth control options may be considered to prevent pregnancy as well.NAM aidsmap: "Undetectable viral load and transmission – information for people with HIV" CDC PrEP Basics CDC Condom Effectiveness
14. What does U=U mean for me if I don’t have HIV?
You don’t need to be afraid of getting HIV when your sexual partner is undetectable. As stated in the NAM aidsmap resource “Undetectable viral load and transmission – information for HIV-negative people”, “If you have a partner with HIV who is on treatment and has an undetectable viral load, they will not pass HIV on to you – even if you don’t use condoms. However, if you have other sexual partners, you could still contract HIV outside the relationship, possibly from someone who does not know that they have HIV. In these instances, prevention methods such as condoms or PrEP may still be important.” It is important to remember that while an undetectable viral load will prevent transmission of HIV, it does not protect you or them from other sexually transmitted infections (STIs) or unwanted pregnancy. Condoms are highly effective at preventing STIs. Condoms and other birth control options may be considered to prevent pregnancy as well.NAM aidsmap: "Undetectable viral load and transmission – information for HIV-negative people" CDC PrEP Basics CDC Condom Effectiveness
15. What does this mean for reproductive health, such as conception, pregnancy, and breastfeeding/chestfeeding?
Knowing that an undetectable viral load prevents HIV transmission through sex may be especially useful for people wishing to conceive a baby without using assisted reproduction methods. An undetectable viral load also dramatically reduces the risk of transmission during pregnancy, birth, or breastfeeding. For more information on HIV and reproductive health, such as pregnancy and breastfeeding/chestfeeding, please refer to the sources below.The Well Project: "Breastfeeding, Chestfeeding and HIV: Supporting Informed Choices" Human Reproduction: "People living with HIV and procreation: 30 years of progress from prohibition to freedom?" The Well Project: "Breastfeeding and HIV in the Era of U=U: Highlights from a Growing Discussion" HIVE Online: "Women Living with HIV" CDC: Effectiveness of Prevention Strategies to Reduce the Risk of Acquiring or Transmitting HIV
16. Should I stop using condoms and/or PrEP if I’m with someone who is undetectable?
PrEP and/ or condoms are not necessary to prevent HIV when the sexual partner living with HIV has an undetectable viral load. Having an undetectable viral load, using PrEP, and using condoms are all HIV prevention strategies that people can choose to use alone or in combination. We provide information about the latest science of HIV transmission so people with HIV and their partners can make informed decisions about what works for them. Some people may prefer to use several HIV prevention strategies for a variety of reasons such as to reduce transmission risk anxiety, because they have sex with more than one person, to prevent other STIs, to prevent pregnancy, or if the partner with HIV has challenges with ART adherence. Condoms, when used correctly, are the only method that helps prevent HIV, some STIs, and pregnancy.
It may take time for an HIV-negative person to trust in their partner being truly undetectable and that that will keep them safe from HIV. As the study cited below showed, it can take time, sometimes years. Partners living with HIV can see it as evidence they are not trusted, when it may be that anxiety from the HIV-negative partner is about coming to terms with new information. In the meantime, other strategies are possible including PrEP.CDC Condom Effectiveness CDC PrEP Basics CDC: Effectiveness of Prevention Strategies to Reduce the Risk of Acquiring or Transmitting HIV NAM aidsmap: "The work of a couple: how gay men in relationships come to trust that “Undetectable = Untransmittable”"
17. Do I need to disclose my HIV status to my sex partner if I am undetectable?
As long as you have an undetectable viral load and you continue to take your ART as prescribed you are not putting your sex partners at risk. It is a highly personal decision whether or not to share your status with a partner. There is no single right answer to whether there is an ethical duty to share your status when you are not putting your partner at risk. However, you may want to consider the pluses and minuses of sharing your status for you and your partner. A partner may become upset if they learn about your status after sexual interaction and it can cause unnecessary interpersonal consequences even when several scientific studies (see question 1) have proven that there is no risk of transmission. Also, it’s extremely important to keep in mind that many discriminatory HIV criminalization laws exist in some states and parts of the world that require you to disclose your status even when there is no risk of transmission. To learn more about the HIV criminalization laws in your state and country, visit HIV Justice Network.HIV Justice Network HIV Legal Network: "HIV Disclosure to Sexual Partners" Consensus Statement on HIV "Treatment as Prevention" Center for HIV Law and Policy SERO Project
18. Can I trust that my partner is really undetectable?
Just like you cannot tell if someone has HIV or is taking PrEP by looking at them, you also cannot tell if someone has an undetectable viral load by how they look. Whether or not you choose to trust your partner is a highly personal decision and is likely to depend upon your sexual practices and relationship circumstances. People engaged in consensual sex are responsible for their own sexual health. In some circumstances, PrEP is an empowering option to protect yourself against HIV transmission without having to depend on others. If all parties agree, attending a medical visit with your partner and getting viral load info from the provider can be a way to increase trust.CDC PrEP Basics Planned Parenthood: Healthy Relationships
19. Does U=U apply to transmission through needle sharing?
U=U does not apply to HIV transmission through sharing syringes or other injection equipment needle sharing. There is not yet enough research to draw a conclusion. There is some evidence from a 2013 study in Bangkok, Thailand, that treatment reduces the chance of transmission via needle sharing, but more research is needed. Harm reduction services (needle exchanges, supervised injection sites, etc.) are critical to supporting the health of injection drug users and preventing HIV transmission. For help regarding addiction and treatment, please visit the link below.Antiretroviral prophylaxis for HIV infection in injecting drug users in Bangkok, Thailand (the Bangkok Tenofovir Study) DrugRehab.com
20. Why isn’t my medical provider telling me this information?
Unfortunately, some medical providers are not up-to-date with the current science. Others agree with the science but are concerned about 1) an increase in condomless sex among people with HIV which may result in an increase in other STIs; 2) patients’ potential lack of understanding that maintaining an undetectable viral load requires excellent treatment adherence and monitoring; and 3) if people with HIV interrupt their treatment by choice or circumstances outside of their control, their virus will likely rise to detectable levels. Some medical providers selectively choose to discuss this information only with patients and clients whom they judge are “responsible” (for example: monogamous and with a stable linkage to treatment) rather than directly address the concerns described above through education. There is no medical or ethical justification to withhold this information. It is essential for medical providers to inform their patients about the benefits of treatment.The Lancet: Providers should discuss U=U with all patients living with HIV
Thank you to our partners at NAM aidsmap for providing feedback and input on these FAQs.