This is what it means to have undetectable HIV

U=U#UequalsUUndetectable = Untransmittable

Whether you’ve seen this somewhere or not, you’ve got to admit it’s catchy. But do you know what it means?

In 2016, U=U exploded across the globe, pushed by the Prevention Access Campaign. U=U is a slogan that tries to spread a simple message: undetectable = untransmittable. More specifically, having an undetectable viral load of human immunodeficiency virus (HIV) = being unable to transmit HIV to a sexual partner (Prevention, n. d.).

The scientific evidence behind U=U and the efforts to get the message out there are huge (NIAID, 2019). Since it was first discovered in the 1980s and dubbed gay-related immune deficiency (GRID), HIV and its later stage, acquired immunodeficiency syndrome (AIDS), have been shrouded with stigma. Out of fear of spreading the virus, some people with HIV refrain from sexual contact or from bearing children.

U=U allows these fears to be put on the backburner. Individuals who have undetectable levels and remain undetectable and adherent to treatment can engage in sexual behavior without worrying about transmitting the virus to a sexual partner. Mothers living with HIV also have a significantly reduced risk of transmitting the virus to their child through birth or breastfeeding. And having undetectable levels doesn’t only mean good news in terms of transmission. If levels of the virus are undetectable, it means treatment is effective, the virus isn’t multiplying as quickly, and CD4+ levels can remain high, significantly slowing the progression of HIV into its later stages and into AIDS. In fact, studies have shown that viral suppression can increase life expectancy in people with HIV (May, 2014).

Since it is always possible for viral levels to come back up (even without you knowing it), exact recommendations regarding which behaviors are safe to engage in should be discussed with your healthcare provider.

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To provide some background before digging back into what undetectable means: HIV is a virus that infects humans. More specifically, HIV is a virus that infects the CD4+ T cells of the human immune system.

HIV is a sexually transmitted infection (STI), but it can also be transmitted from mother to child during pregnancy and breastfeeding or through contact with infected blood, such as by sharing needles during intravenous drug use. Approximately 70% of new cases of HIV in the United States affect men who have sex with men (MSM) but everybody, including women and infants, can potentially acquire HIV.

HIV infection progresses in stages that are characterized by different symptoms. Even without treatment, the full progression of HIV from exposure to end-stage AIDS can take over ten years.

The stages of HIV are:

1. Acute infection: This is characterized by a flu-like illness that typically shows up two to four weeks after exposure. The most common symptoms are fever and swollen lymph nodes.

2. Clinical latency (chronic infection): This stage occurs after the body mounts a reaction to the initial infection and drives the viral load down. This period can last approximately ten years and is typically asymptomatic. However, without treatment, the viral load slowly rises, and CD4+ T cell levels slowly fall in the background. 

3. AIDS: This a late stage of HIV and that is defined by having either a CD4+ T cell count of <200 cells/mm3 or an AIDS-defining illness. Individuals with AIDS are at increased risk of acquiring opportunistic infections, which are infections that may not normally cause complications in an HIV negative (HIV-) individual but can in someone who is living with HIV.

Once infected with HIV, the virus eplicates inside the body. This means that the virus uses the host’s cells to create more of the virus, so it can continue spreading. The amount of HIV in the body is called the HIV viral load and is measured in the amount of “copies” of the virus in a given volume. More copies means there is more of the virus in the body; fewer copies means there is less of the virus in the body.

As part of regular care, people with HIV should have their viral load checked routinely. This can give an individual and their healthcare provider an indication of how well HIV is being managed and whether treatment is working. A viral load that does not decrease could mean someone is not adhering to medication or that different treatments need to be attempted. According to HIV.gov, people with HIV should have a viral load checked every three to six months, before starting any new HIV medication, and two to eight weeks after starting or changing any HIV medications (HIV.gov, 2017).

Treatment for HIV is called antiretroviral therapy (ART). Most people who are adherent to ART every day can attain undetectable levels within six months. Exactly how long this takes depends on individual factors like genetics, the strain of HIV that an individual has been infected with, and whether the strain has developed any sort of resistance to antiviral medications. If somebody has maintained undetectable levels for six months after their first undetectable viral load, they are said to have “durably undetectable” levels (NIH, n.d.).

Having undetectable levels of HIV means levels of the virus are so low that lab tests aren’t able to detect the virus in the blood. Most labs are unable to detect fewer than 50 copies/mL of the virus, so the definition of having an undetectable viral load typically means you have <50 copies/mL. According to HIV.gov, undetectable values can range from <40-75 copies/mL (HIV.gov, 2017).

It is important to remember that having undetectable HIV is not synonymous with being cured. Although levels of the virus are lower than can be detected by current testing, it is still present in small amounts. In addition, HIV is a type of retrovirus, which means it incorporates its genetic material into the genetic material of the cells it is infecting. This remains the case even if somebody has undetectable levels. Therefore, if somebody who has undetectable levels goes off of his or her medication or isn’t always taking it as prescribed, viral levels will come back up again, and they will no longer be considered to have undetectable HIV. HIV requires lifelong treatment; currently, there is no cure for HIV.

The core message is this: You cannot get HIV through sexual contact from somebody living with HIV who has had an undetectable viral load for at least six months (NIH, n.d.). This has revolutionized the way people with HIV live and is also great news for public health workers and anybody else who has an interest in HIV prevention. Achieving undetectable levels gives everybody who has HIV a goal of treatment and is a powerful step towards ending the HIV epidemic.

The common methods of HIV transmission include via sexual contact, from mother to child during pregnancy and childbirth, or through sharing needles during intravenous drug use. According to the Centers for Disease Control and Prevention (CDC), the risk of somebody with undetectable HIV transmitting the virus through any of these methods is as follows (CDC, 2019):

• Sexual contact: There is effectively zero risk of transmitting HIV from an HIV-positive partner with undetectable levels to an HIV-negative partner through anal sex, oral sex, or vaginal sex.

• Pregnancy: The chances of a mother who's undetectable transmitting HIV to the newborn during pregnancy, labor, and delivery can be <1%. This means the woman can plan for a vaginal delivery, as a Caesarean delivery (which is offered to mothers with HIV who do not have undetectable levels) offers no additional protection regarding the risk of transmission. And according to the American College of Obstetricians and Gynecologists (ACOG): “[V]aginal delivery is appropriate for HIV-infected pregnant women who have been maintained on cART [combined ART] and who have viral loads of 1,000 copies/mL or less at or near delivery. These women can be managed in a manner similar to HIV-uninfected women” (ACOG, 2018).

• Breastfeeding: It is still possible to transmit HIV during breastfeeding, even when the mother has undetectable levels of the virus. Because of this, the United States recommends that mothers with HIV do not breastfeed their infants.

• Sharing needles: The risk of HIV transmission is likely lower when a needle partner has undetectable levels. However, there currently isn’t enough evidence to know for sure. Abstaining for injection drug use is still the best way to avoid transmission by this method.

While attaining an undetectable level of HIV is one prevention method, There are other ways to decrease the spread of HIV. Practicing safe sex (i.e., avoiding condomless sex) can decrease the risk of transmission in serodiscordant couples (sexual partner where one individual has HIV and one individual is HIV-). Additionally, people who don't have HIV can take medications like Truvada, generic Truvada or Descovy as pre-exposure prophylaxis (PrEP), which can reduce the risk of acquiring HIV from sex by about 99% when taken correctly (CDC, n.d.).

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Current version

September 22, 2019

Written by

Mike Bohl, MD, MPH, ALM

Fact checked by

Tzvi Doron, DO

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About the medical reviewer

Tzvi Doron, DO

Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine.