A new study has emerged from Kaiser researchers claiming that PrEP, an HIV prevention drug, is 100% effective at preventing the disease.

The study, published by the Clinical Infectious Diseases journal, found that of the 650 people who used the drug PrEP, all were HIV negative, according to TIME.

The drug is composed of emtricitabine and tenofovir, but many know the drug by its popular brand name - Truvada.

The drug is not new, as it has been available since 2012 when the FDA approved daily PrEP for those who were at risk of contracting the disease. There have been other trials in the past showing high levels of success, but the recent trial is notable because it is the first to find PrEP 100 percent effective, according to Fox News.

Critics have their own sets of concern about the pill however, saying that it encourages unsafe sex.

Michael Weinstein of the Los Angeles Aids Healthcare Association echoed concerns saying that while it is a good alternative for those who engage in unsafe sex, it should not be used as a community wide prevention tool, according to SF Gate.

Participants in the study were all sexually active and although none became infected with HIV, more than half tested positive for other sexually transmitted diseases.