A new study about the prescription drug Truvada backs earlier research showing it can protect against HIV infection.

A paper presented at the International AIDS Conference in Melbourne, Australia, detailed the result of a study that examined the effect of Truvada on 1,600 gay men and transgender women.

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The participants were involved in an earlier study that showed Truvada lowered the risk of HIV infection.

In the follow-up study, 75 percent of the participants agreed to continue taking the pills for 17 months. The results were encouraging, said Dr. Robert Grant, an AIDS expert at the Gladstone Institutes.

Among the findings was that none of the participants became infected when they took the drug at least four days a week, and that although some doses were missed the risk of infection was still lower than not taking the pill at all.

Michael Warren, head of a nonprofit organization that conducts studies on HIV prevention, said the study showed that Truvada worked and should be made available to people at risk of getting HIV.

The study, which was also published in the British journal Lancet Infectious Diseases, took place in several countries, including the U.S. and Thailand. The U.S. National Institutes for Health provided the funding.

While the Centers for Disease Prevention and Control recommended Truvada earlier this year as a means to protect at-risk groups against HIV infection, some health officials warned that taking the pill might give people a false sense of security and encourage promiscuity.

There were also concerns that with Truvada men might think that they no longer need to use protection when engaging in sexual activities.

The study did not find that Truvada increased risky behaviors since there was no rise in sexually transmitted diseases such as herpes or syphilis. 

Truvada, manufactured by Gilead Sciences Inc., won approval from the U.S. Food and Drug Administration in 2012 as a drug designed to reduce the risk of HIV infection in people at high risk for contracting the AIDS virus.

TagsTruvada, AIDS research, International AIDS Conference