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Scientists have found that taking the daily antiretroviral pill Truvada, which is already on the market, greatly reduces the chances of HIV infection.

In a large-scale international study of 2,500 men who have sex with men, investigators found a 44 percent reduction in HIV infection for those taking the drug, and a 90 percent reduction for those who never skipped doses. Advocates and doctors alike say this proves there is yet another weapon in the armory for HIV prevention, specifically for gay men.

"I think for the first time we may be able to find something that may effectively change the HIV epidemic not just here in the U.S. but across the world," said Associate Medical Director at St. Luke's Roosevelt Comprehensive HIV AIDS Center Dr. Tony Urbina.

The pills are also known as pre-exposure prophylaxis or PreP. With still 55,000 new infections nationwide each year, doctors and researchers say PreP might be an increasingly useful tool where it is difficult to get people to change their behavior, particularly sexual behavior. Some doctors already prescribe the pill, and with news of this latest research prescriptions are likely to grow. While experts in the field of HIV and AIDS research say there's lots of room for celebration, it is not a replacement for common sense.

"This study proves that there is hope. But hope is not a strategy neither is it a cure. So gay men will still have to practice safe sex. They will still have to use condoms. And for the individuals who are using PreP they'll have to do it on a daily basis to increase the efficacy," said Gay Men's Health Crisis CEO Marjorie Hill.

Doctors also caution that researchers need to take a closer look at whether it was the use of Truvada, a change in behavior or both that lowered the risk for participants in the study.

"In this trial both groups those that were given the medication and those that got a dummy pill. Both of them were counciled to safe sex, and use of condoms still an important in risk reduction in preventing HIV infection. So really can't be throwing condoms out the windows. I think this is something we can add to these other prevention measures," Urbina said.

Whether the research will trigger a national shift in prevention policy remains to be seen. More research needs to be done and the testing of PreP needs to be expanded to more groups to ensure its effectiveness and safety.