Truvada has been on the market since 2004 to treat people who already have the AIDS virus. But after studies showed it could help prevent infection among gay and bisexual men, U.S. health officials last year said doctors could prescribe it as a preventive for men at high risk.
Since then, studies have found it also can prevent the virus in women and heterosexual men.
Last month, the Food and Drug Administration formally approved the sale of Truvada as a preventive measure for healthy people at high risk of getting HIV.
The CDC is not recommending the pill for all sexually active heterosexuals. And even among couples where one person has HIV, regular condom use generally is effective protection.
But the pill would be a good option for a couple who wanted to have a baby, Smith said.
The drug's manufacturer, Gilead Sciences Inc., said this week it's difficult to break down what portion of Truvada sales have been for prevention.
When used as a preventive, the pill is taken once a day. It costs between $6,000 and $12,000 a year, although some private insurers and Medicaid programs have been covering it, Smith said.
The CDC also had new advice about treatment for another sexually transmitted disease - gonorrhea.
Health officials are recommending that whenever possible, doctors stop using an antibiotic commonly used to treat it. They're worried about signs that gonorrhea is becoming resistant to it.
The antibiotic is a pill called cefixime, and it belongs to the last remaining class of drugs effective for gonorrhea. The one remaining recommended drug is a shot called ceftriaxone.
Cefixime is still effective in most cases. But officials feel they can't take a chance that the resistance they've begun to see will continue. If it does, that could also strengthen gonorrhea to resist ceftriaxone, they believe.
"This change is a preemptive strike" to preserve the last treatment option, said Gail Bolan, who oversees the CDC's sexually transmitted diseases prevention programs.
Gonorrhea, once known as the clap, was once the scourge of soldiers and sailors. It was tamed by penicillin, but the germ is now resistant to that and to several drugs that followed.
Gonorrhea is still one of the most common sexually transmitted diseases, with about 300,000 new cases reported annually.
