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 or under 200 copies/mL viral load cannot transmit HIV through sex. For information about HIV transmission through perinatal transmission (from mother/parent 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: "The role of HIV viral suppression in improving individual health and reducing transmission: policy brief""
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. 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. 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 a laboratory test. This is called ‘having an ‘undetectable viral load,’ which eliminates sexual transmission of HIV while simultaneously improving the health of a person living with HIV. This is usually under 40 copies/mL, but the lower limit of detection varies by the type of test used. Having an undetectable viral load 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. Having an undetectable viral load is the ultimate goal of ART.
– Viral suppression: The measurement used to define “viral suppression” may differ depending on the health agency. For instance, the US Centers for Disease Control and Prevention (CDC) defines viral suppression as less than 200 copies/mL. According to the CDC, a person with HIV who takes ART as prescribed and “gets and stays virally suppressed can stay healthy and will not transmit HIV to their sex partners.” However, the World Health Organization (WHO) defines a “suppressed but detected” viral load as 1,000 copies/mL and below. According to the WHO, a viral load that is 1,000 copies/mL and below means there is “almost zero or negligible risk” of sexual transmission. Excellent adherence, or taking ART as prescribed by a healthcare provider, is important to maintain viral suppression.
Because the exact numbers for “virally suppressed” may continue to change, it is important to note that any undetectable test result or a detectable result that shows a number less than 200 copies/mL indicate that HIV is untransmittable, and the risk of sexual transmission is zero.HIV Treatment as Prevention World Health Organization (WHO): The role of HIV viral suppression in improving individual health and reducing transmission: policy brief
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?
Yes, the risk is zero. People living with HIV who have an undetectable viral load or a viral load under 200 copies/mL have zero risk of transmitting HIV through sex as long as they continue to take their antiretroviral therapy as prescribed.World Health Organization (WHO): The role of HIV viral suppression in improving individual health and reducing transmission: policy brief CDC Effectiveness Estimates: Viral Suppression "100% effective" at preventing HIV transmission 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 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.
People living with HIV who have a detectable viral load of under 200 copies/mL have zero risk of sexually transmitting HIV. People living with HIV who have a detectable viral load of 200 to 1000 copies/mL have almost zero or negligible risk of sexually transmitting HIV. Staying on treatment is important to maintain a low viral load.
For people living with HIV with detectable viral loads above 200 copies/mL, there are effective options to prevent HIV, including condoms, and in some parts of the world, PrEP. 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" World Health Organization (WHO): "The role of HIV viral suppression in improving individual health and reducing transmission: policy brief""
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 prevent 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"
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. When a sexual partner has an undetectable viral load, the risk of sexual transmission is zero, even without condoms or PrEP.
Having an undetectable viral load, using PrEP, and using condoms are HIV prevention strategies that people can choose to use alone or in combination. 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 partners to trust that an undetectable viral load will prevent HIV transmission. 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.
It is important that both partners make informed decisions about what works for their relationship and circumstances.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 it is scientifically established that there is zero 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 zero 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.