What’s the difference between being virally suppressed and being undetectable?

More and more people understand that undetectable equals untransmittible (or U=U). So World Health Organization (WHO) guidance on the difference between being undetectable and being virally suppressed is timely.

What is this story about?

The WHO has published a new HIV viral suppression policy briefing for people with HIV, healthcare providers, programme staff, policymakers and others working in the HIV response.

Why is this important?

There is a need for clear understanding of what different HIV viral load measurements mean for people’s health and the risk of HIV transmission.

What does the policy brief say?

The brief describes three viral load levels using a traffic-light system of red, amber and green.

Level 1 (Red)

Unsuppressed: viral load is more than 1,000 copies/mL

Having an unsuppressed viral load while taking antiretroviral treatment (ART) suggests treatment is failing. It can also indicate drug resistance. The risk of HIV transmission increases as someone’s viral load rises.

Level 2 (Amber)

Suppressed but detectable: viral load is 1,000 copies/mL or less

People with HIV who have a suppressed but detectable viral load and are taking medication as prescribed have “almost zero or negligible risk” of passing HIV on through sex.

Level 3 (Green)

Undetectable: viral load not detectable in tests

People with HIV who have an undetectable viral load and continue taking medication as prescribed have zero risk of passing HIV on through sex.

HIV viral suppression is critical for individual health. Being undetectable provides the best health protection for someone with HIV.

Having a suppressed but detectable viral load (between 200 and 1,000) suggests treatment failure is likely to happen. People in this position should get enhanced adherence counselling and follow-up viral load testing. If they remain suppressed but detectable they should change medication.

If a woman with HIV has a suppressed but detectable viral load during pregnancy, delivery and breastfeeding she is unlikely to pass HIV on to her infant. The risk can be less than 1%.

If a woman with HIV is undetectable before getting pregnant and throughout pregnancy, delivery and breastfeeding, there is no risk of HIV being transmitted to the infant.

There is no research yet on how being undetectable or suppressed but detectable affects HIV transmission through injecting drugs.

The brief also looks at the type of viral load tests to use. Plasma samples provide the most sensitive results, but alternatives, like point-of-care testing and dried blood spot samples, still provide high-quality results. And because they are less expensive, using them will enable more people to access viral load testing.

What does this mean for HIV services?

The message that an undetectable viral load is the ultimate goal of ART for people’s own health and to prevent transmission to their sexual partners and children should be reinforced at every HIV care visit.

People with HIV who have an undetectable viral load should be made to feel confident that there is no risk of transmitting HIV through sex as long as they continue to take ART as prescribed.

People with HIV who have a suppressed but detectable viral load should be told there is almost no risk of transmitting HIV through sex as long as they continue to take ART as prescribed. They should get adherence support so they can become undetectable, plus another viral load test in three months.

People with HIV need access to viral load testing to realise the benefits of ART. It is important to advocate that alternative viral load testing methods are made available so that more people with HIV can keep track of their viral load.