Transmission of drug-resistant HIV

  • Around one in ten people with new HIV infections have resistant virus.
  • Resistant mutations acquired at the time of infection may persist for many years in the absence of treatment.
  • Having resistant virus may reduce later treatment options.

HIV can become resistant to the drug used to treat it. This is because HIV changes, or mutates, slightly every time it reproduces itself. Some of these mutations are in the part of the virus that is targeted by anti-HIV drugs and can mean that anti-HIV drugs don’t work as well against some strains of the virus.

Viral resistance occurs when the drug levels in the bloodstream are not high enough to stop HIV from reproducing. Suboptimal drug levels can result from missed or incorrectly taken doses, ones that are not absorbed or metabolised properly, or because of interactions that may occur with other drugs or food.

Sexual transmission of drug-resistant strains of HIV is well documented. While studies from the late 1990s suggested that less than 10% of new infections were of drug-resistant virus, recent studies suggest that many newly infected individuals are infected with an at least somewhat drug-resistant strain of HIV. As the uptake of antiretroviral therapy has spread, so has the transmission of drug-resistant virus.

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This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.