Over a quarter of all new AIDS cases in the U.S. are found in heterosexuals who do not inject drugs. To prevent some of these infections, the CDC is recommending that certain heterosexuals at risk for contracting the AIDS virus consider taking the once-a-day pill Truvada.

The CDC has begun to counsel doctors, who must prescribe the medication, to offer it to those heterosexuals at highest risk, such as those whose partner is HIV-positive. People who fall into this category should consider discussing this option with their doctor.

There are nearly 50,000 new HIV infections in the U.S. every year.

Use of Truvada for reducing the risk of contracting HIV in high-risk adults was approved by the FDA in July. The medication received initial approval in 2004. In the past few days, Truvada's effectiveness has been underscored by a study finding that even less-than-perfect adherence to the once-daily regimen offered protection rates reaching 90%.

The CDC does not recommend Truvada for all heterosexuals who are sexually active, only for those at highest risk of contracting HIV. And the CDC stresses that condoms are still the best first-line defense against AIDS.

Women who want to take Truvada should have a pregnancy test before starting to take the pill. So far, Truvada doesn't seem to present any risk to the unborn child during pregnancy, but most information has come from children born to HIV-positive mothers who were taking Truvada. There's little information on uninfected mothers who became pregnant while taking Truvada. So its safety during pregnancy is one more issue that needs to be discussed with a doctor.

There are nearly 50,000 new HIV infections in the U.S. every year. Most of the focus on reducing this number has been on protecting homosexuals and intravenous drug users, those most susceptible to becoming infected. The CDC thinks it's now time to begin focusing on higher-risk heterosexuals, too.

The CDC recommends that only people who can expect to follow the dosage regimen, take Truvada daily and have periodic tests to confirm that they're HIV-negative be seen as good candidates. The new study, published in Science Translational Medicine, suggests broader outlines may soon follow.

Truvada will cost between $6,000 and $12,000 per year. Medicaid and some private insurance may cover it.

The CDC recommendations can be seen both in a press release and in an article in Morbidity and Mortality Weekly Report, published by the CDC.