HIV undetectable and breastfeeding

It is widely accepted that there is no risk of sexual transmission of HIV if you have an undetectable viral load. However, when it comes to breastfeeding there are still concerns in the scientific community.

Antiretroviral treatment (ART) keeps people living with HIV healthy, but it’s also a powerful prevention tool. We now know that with effective HIV treatment, people living with HIV can suppress the virus to an undetectable level which makes the risk of sexual transmission of HIV equal to zero (known as ‘Undetectable = Untransmittable’ or U=U).

The U=U movement has unburdened thousands of people living with HIV with the knowledge that they cannot give HIV to their partners through sex if they are virally suppressed. But there has so far been no consensus on declaring U=U for breastfeeding. Why is that? Why are breastfeeding guidelines different? What does the science say about breast milk and HIV transmission?

Thirty years into the response, there are still a number of unanswered questions around the exact mechanism by which a baby can become infected via breast milk. There also remain questions about the viral load of HIV in blood versus the viral load in breast milk, and what a ‘safe’ threshold is for transmission. This is why scientists and policymakers have yet to declare U=U for breastfeeding.

It is known that HIV particles and HIV-infected cells are present in breast milk, and there is a clear link between the mother having a high viral load and the baby becoming infected, which is why it is important for the mother to be on treatment while breastfeeding to reduce her viral load.

In scenarios where women do not have access to antiretroviral treatment, up to 20 percent of infants will become infected with HIV through breastfeeding if they weren’t already infected during pregnancy or childbirth. Where treatment is available, this risk can be reduced to below one percent in the real world.

So despite the many unanswered scientific questions, we do know the actual risk of HIV transmission is extremely low when the mother has access to suppressive ART.

According to researchers in a recent scientific viewpoint, most of the cases of mother-to-child transmission during breastfeeding can be partly explained by either detectable virus or poor adherence.

So until our understanding of the science improves, guidelines are unlikely to recommend breastfeeding for mothers with an undetectable viral load in high-income countries any time soon.

But we know that breastfeeding has multiple benefits over formula feeding for the baby, such as anti-inflammatory effects, improvements in the baby’s immune system, improvement in the development of the gut microbiome, and better overall health and psychological outcomes in the long-run. 

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