A significant proportion of people contract HIV that is already resistant to one or more anti-HIV drugs. This can happen either through sexual transmission, through contact with infected blood (e.g. through injecting drugs), or from an HIV-positive mother to her baby.

Becoming infected with a drug-resistant strain may limit your treatment options in the same way as developing resistance while taking treatments does, narrowing down the range of drugs you might benefit from.

In the UK, about 10% of people newly infected with HIV have drug-resistant virus.

If you have a detectable viral load and drug-resistant virus, then there’s a risk that you could pass on a drug-resistant strain of HIV to someone else. Properly used condoms are a very good way of preventing sexual transmission of HIV.  

It is becoming clear that somebody who is already HIV-positive can be infected with another strain of HIV that could be drug-resistant. This is called superinfection. It is not known how common this is, but so far it appears to be rare, and only 40 or so cases from around the world have been recorded. However, this figure is increasing as new cases are reported. If you would like to discuss any concerns you may have about this, such as how it might affect the sex you have, a health adviser or health trainer at your HIV clinic or another member of your healthcare team should be able to help. You can also read more about superinfection in the NAM booklet in this series, HIV & sex.