Treatment experts say it's particularly good news that the most advanced experimental drugs are effective against drug-resistant HIV. About 10% of newly diagnosed adults are infected with virus already resistant to at least one antiretroviral, according to the Centers for Disease Control and Prevention. Joel Gallant, MD, associate director of Johns Hopkins AIDS Service in Baltimore, says some surveys put the percentage as high as 15% to 20%.
Drug-resistant HIV is spread by people whose virus has evolved to a point that it's not vulnerable to medications they're taking, often because of poor adherence to meds or after their long-term use. A drug-resistant strain can then be transmitted to other people, leaving them resistant to the same anti-HIV drugs from the moment they're infected.
CDC data show that levels of drug resistance among people newly infected vary significantly by drug class, with resistance to nonnucleoside reverse transcriptase inhibitors the most common. Especially worrisome, however, is that about 2% of people newly diagnosed are resistant to drugs in two or more classes of medications.
'These people are already starting off behind the eight ball in terms of treatment options,' warns Rowena Johnston, Ph.D., vice president of research at the American Foundation for AIDS Research. 'And they're why it's vital that we keep discovering new medications that attack HIV in new ways'so that we have drugs that can control their infection and keep them alive.'