The number of people with HIV that is resistant to some anti-HIV drugs has fallen significantly in recent years, according to a recent Swiss study.

A drug-resistant HIV strain is one which is less susceptible to the effects of one or more anti-HIV drugs. Having drug-resistant HIV limits the range of drugs you can use, but you will still usually be able to find an effective treatment. Drug-resistant HIV can emerge if you regularly miss doses of your anti-HIV drugs or take them late. Because HIV treatment is now easier to take, with fewer side-effects, resistance is less of a problem than it used to be.

Looking back at data on thousands of people living with HIV in Switzerland between 1999 and 2013, the researchers found that in 1999 there were 401 patients with a new case of drug resistance, including 69 people who had resistance to multiple drugs. Although many more people were living with HIV in 2013, there were only 23 new cases of drug resistance. These new cases of resistance in recent years are mostly due to resistant virus being sexually transmitted – individuals having resistant virus when first diagnosed with HIV.

Other people continue to have resistance to some drugs, as a legacy of problems with HIV treatment from years ago. Looking at those individuals who had resistant virus in 2013, most started to take HIV treatment before 2006. Only 15% of cases involved people who began HIV treatment after 2007.

The full article can be read here.

There’s more information about drug resistance and how to prevent it in NAM’s booklet ‘Taking your HIV treatment’.