Learning objectives
By the end of this section you will be able to:
- Explain to your patients the effects that viral load blips and low level viraemia might have on HIV transmission risk.
- Explain that having a sexually transmitted infection (STI) does not impact on HIV transmission risk in the context of an undetectable HIV viral load.
- Answer questions from your patients about PEP and PrEP, and when these preventative methods are required.
- Know what the implications of U=U are on criminalisation of HIV and address concerns about reckless transmission.
- Explain to your patients the implications of having an undetectable viral load on breastfeeding.
What this page covers
- Adherence.
- Blips in viral load.
- Low-level viremia.
- STIs.
- How does PEP and PrEP fit with U=U.
- Impact of U=U on the criminalisation of HIV.
- Implications of U=U for breastfeeding and other HIV transmission risks.
Dealing with difficult questions
This video is divided into the following chapters, which you can access within the video using the scroll bar:
Introduction and viral load (0:00), Adherence (3:08), Viral load blips (4:16), Low-level viraemia (5:09), STIs (6:18), Breastfeeding (7:00), Other forms of transmission (8:07), How PrEP and PEP fit within U=U (8:16), Criminalisation (8:36), Continuum of care (9:48).
Key messages from video
The meaning of 'undetectable'
Viral load tests measure the amount of RNA (the virus’ genetic material) in a sample of blood and the results are given as the number of RNA copies per millilitre (copies/ml).
HIV therapy works by stopping the virus reproducing and suppresses the viral load to undetectable levels.
Laboratories in the UK can detect viral loads as low as 20 or 50 copies/ml. Therefore, for an individual, an undetectable viral load could be <20 or <50 copies/ml. This means the virus is still there but in such small amounts the laboratory machines can’t detect it.
An undetectable viral load in terms of preventing HIV transmission is defined as anything less than 200 copies/ml. When the viral load is <200 copies/ml there is a zero risk of HIV transmission to sexual partners.
The time it takes to achieve an undetectable viral load varies between individuals but we would expect somebody to become undetectable within three to six months of starting treatment.
Once the viral load is undetectable it is important that people are adherent – meaning they continue to take their treatment as prescribed – and have their viral load monitored regularly to ensure they remain undetectable.
Once an individual has achieved an undetectable viral load, if they are adhering well and taking their medication as prescribed, then they can be confident their viral load will remain undetectable and they can’t pass on the virus to others.
Viral load blips and low-level viremia
A viral load blip is when the viral load, which was previously undetectable, becomes detectable but at a very low level (often <100 copies/ml). If this occurs in the context of someone adhering well to their medication then it's nothing to worry about, as the viral load will return to undetectable levels when the test is repeated.
Viral load blips that are <200 copies/ml do not increase the risk of HIV transmission. As long as the viral load remains <200 copies/ml, the transmission risk is zero.
Where there is low-level viraemia, where someone’s viral load is not undetectable but is still <200 copies/ml, the transmission risk remains zero.
If someone has a viral load over 200 copies/ml, then U=U does not apply and there is a risk of transmission.
The effect of STIs and other infections on U=U
Having an STI does not affect U=U. In the Partner studies, many individuals reported having STIs but there were still no transmissions when the positive partner had an undetectable viral load.
Having other infections such as colds, flu and gastroenteritis will not affect U=U as long as good adherence is maintained.
U=U and breastfeeding
U=U only applies to the sexual transmission of HIV. It does not apply to breastfeeding.
In the UK, we advise that people living with HIV do not breastfeed as there are safe alternatives such as formula feed and clean water to mix it with.
Some people may choose to breastfeed and it's important they are supported to do this safely by:
- Ensuring they are adhering to treatment.
- Having more frequent viral load testing.
- Breastfeeding for as short a time as possible.
- Avoiding getting cracked or infected nipples.
Further information on breastfeeding and leaflets for people living with HIV:
U=U only applies to sexual transmission
U=U only applies to sexual transmission. It does not apply to injecting drug use or any other way that HIV may be transmitted e.g. needlestick injuries.
PrEP and PEP
People living with HIV who have an undetectable viral load have a zero risk of transmitting the virus to their sexual partners. Pre-Exposure Prophylaxis (PrEP) and Post-Exposure Prophylaxis (PEP) are not needed if an HIV negative individual has sex with someone who is HIV positive, is on treatment and has an undetectable viral load.
HIV negative individuals only need PEP or PrEP if they have condomless sex with somebody who does not know their HIV status or somebody who is HIV positive but has a detectable viral load.
Criminalisation
The laws that criminalise HIV transmission or legislate about HIV disclosure vary around the world. The information below relates to the United Kingdom.
In the UK there are no specific laws that criminalise HIV transmission but, since 2004, a number of individuals have been charged or convicted of reckless transmission of HIV. The applicable law in HIV criminalisation cases is the Offences Against the Person Act 1861, which enables prosecution of intentional transmission under Section 18, and reckless transmission under Section 20. Deliberate attempts to infect others are charged under the Criminal Attempts Act 1981.
In England and Wales, a transmission needs to have occurred for a charge of ‘reckless transmission’. In Scotland, however, where the legal system differs, reckless exposure may also be criminalised.
An individual can also avoid liability for reckless transmission if they have taken steps to mitigate the risk of transmission. Although this has not been specifically tested in the courts, U=U is likely to be significant.
Because we're now confident that there is a zero risk of HIV transmission with effective treatment and an undetectable viral load, there should be no concern about criminalisation as a transmission, or an exposure, will not occur. It's still important to talk about HIV criminalisation with people living with HIV as it is often something they will think or be concerned about.
For more information, read an overview for clinicians on the criminalisation of HIV transmissions.
Continuum of care
Based on 2019 figures, in the UK there are now 94% of people living with the virus who know they are HIV positive. 98% of these are on treatment and 97% have an undetectable viral load.
When somebody does not achieve an undetectable viral load:
- It's important not to stigmatise, demonise or marginalise people who, for whatever reason, do not achieve an undetectable viral load. We must ensure we do everything we can to support them to do so.
- There may be socio-economic, mental health or stigma-related reasons why people don’t engage with treatment and care.
- We need to increase our HIV testing efforts to reduce the number of people who are diagnosed late, as well as ensuring that social, psychological and stigma-related barriers are addressed to support engagement in care and adherence to treatment.