There is more good news about HIV treatment pills used to prevent infection in people at high risk of getting the AIDS virus: Follow-up from a landmark study that proved the drug works now shows that it does not encourage risky sex and is effective even if people skip some doses. Mitchell Warren, who heads a nonprofit group that works on HIV prevention research, said in an email from Melbourne that "the story is now clear" that this approach "is real, it works, and it should be made available to people at risk now as part of high-impact combination prevention." Condoms remain the best way to prevent HIV infection but not everyone uses them all the time, so health officials recommend other options for certain groups, such as gay men.