The message of U=U (undetectable equals untransmittable) has been very successful at raising awareness that a person who is on effective HIV treatment cannot pass HIV through sex. It has been taken up as a rallying cry for individuals and organizations all over the world. It has helped to empower people who are on successful treatment to enjoy sex without any fear of passing HIV, and has helped to fight HIV stigma.

While the U=U message has been getting a lot of momentum in recent years, the role of HIV treatment in preventing HIV through other transmission routes is not as widely known. This information is important for informed healthcare decision making and further destigmatizing HIV.

The health benefits of treatment are always the first priority

Whenever we talk about the prevention benefits of treatment, it is important to remember that these benefits are secondary to the health benefits of treatment. If a person living with HIV is not taking treatment, they should first and foremost learn about the ways in which treatment and maintaining an undetectable viral load will help to keep them healthy. Rather than being the main reason that a person should start taking treatment, preventing transmission to others can be an added motivator for people.

HIV treatment and pregnancy

Without successful HIV treatment, HIV can be passed from a person living with HIV to a baby during pregnancy and delivery. The chance of passing HIV during pregnancy or delivery is estimated to be between 15% and 30% without any HIV treatment.

However, taking HIV treatment and maintaining an undetectable viral load dramatically lowers the chance of passing HIV to a baby during pregnancy and delivery. The best evidence for this is from a French study in which no infants were born with HIV, out of more than 2,500 babies born to mothers who started treatment before becoming pregnant, continued treatment throughout their pregnancy and had an undetectable viral load at the time of delivery.

The research on perinatal transmission is not as robust as the research that shows the prevention benefits of treatment and an undetectable viral load for sexual transmission, so there is some disagreement about the message. Some experts are comfortable saying that if a person is on treatment and maintains an undetectable viral load throughout their pregnancy, the baby will not be born with HIV. However, some experts don’t feel that there is enough evidence to make such a definitive statement, and would say that there may be a small risk of transmission.

The lack of a unified message can be confusing for people, but the distinction is one of semantics. Even if there may be a small risk of transmission, the fact is that people who are on treatment and maintain an undetectable viral load throughout their pregnancy and access pregnancy care in Canada are not having babies born with HIV. This is a very good message for people with HIV who want to start a family.

We know of course that not everyone living with HIV is on successful treatment. Even if a person does not have an undetectable viral load before becoming pregnant, starting treatment as soon as possible and maintaining an undetectable viral load for the remainder of their pregnancy will dramatically lower the chance of passing HIV to a baby. This is because HIV is typically passed late in pregnancy or during delivery. So, if a person is able to get their viral load to an undetectable level early in pregnancy, the chance of their baby being born with HIV will be very low.

Overall, the message about HIV treatment for preventing HIV during pregnancy and delivery is a very positive one. For people who want to have babies, this may be just as liberating as the message of U=U.  It means that people who want to have babies can do so without fear of transmission.

HIV treatment and breastfeeding (chestfeeding[i])

Without treatment, the chance of HIV transmission through breastfeeding is estimated to be about 15%.

Being on treatment and maintaining an undetectable viral load dramatically lowers the chance of passing HIV through breastfeeding, but there may still be a small chance of transmission. In Canada, national guidelines recommend that people with HIV not breastfeed their babies. Due to this recommendation, most people living with HIV in Canada choose to feed their babies formula to avoid any chance of transmission.

However, some people have a strong desire to breastfeed for personal, social or cultural reasons. In the case where a person feels a strong desire to breastfeed, some experts agree they should be educated about the risk of transmission so that they can weigh the risk against the benefits of breastfeeding, and if they choose to breastfeed, they should be supported by their doctor to do so in a way that minimizes the chance of transmission. This will likely involve more frequent viral load monitoring for the parent and HIV testing for the infant. It may also involve giving the baby medication for the duration of time when they are being breastfed to further reduce the chance of transmission.

HIV treatment and drug use

Compared to sexual and perinatal transmission, we don’t have as much evidence about how much HIV treatment can lower the chances of passing HIV through shared injection drug use equipment. There is some evidence to suggest that the risk of transmission is reduced when a person is maintaining an undetectable viral load, but we don’t know exactly how much.

People who use drugs have a right to know about the prevention benefit of HIV treatment for reducing the risk of transmission through sharing drug use equipment, even if the risk is not zero. Additionally, people who use drugs also have sex and they have babies, meaning information about the benefits of treatment for preventing sexual and perinatal transmission can be empowering and life-changing for them as well.

The best way to prevent passing HIV through drug use is to use new equipment every time. People who use drugs need access to enough new equipment to be able to do this consistently and to avoid sharing with others.

As we continue to work to spread the U=U message, it’s important that we expand our conversations to include the prevention benefits of HIV treatment beyond sex.

Mallory Harrigan is CATIE’s knowledge specialist in HIV testing. She has a master’s degree in community psychology from Wilfrid Laurier University

[i] Chestfeeding is a term often used by trans people who nurse their babies.

This content was originally published on April 28 2021 at CATIE, Canada’s source for HIV and hepatitis C information