( CNN ) -- For years the message was simple : Use condoms to prevent HIV . But if you are at high risk of contracting the virus , health experts want you to consider an additional strategy -- taking a pill every day to reduce your chance of being infected . New guidelines published by the Centers for Disease Control and Prevention say pre-exposure prophylaxis , or PrEP , should be taken daily by people who are at high risk for contracting HIV . The recommendation is based on several large national and international studies , which were done in varying at-risk populations , such as gay and bisexual men , heterosexual couples where one person is HIV-positive ( the other is not ) and injection drug users . The studies all showed that this drug can help reduce infection rates by more than 90 % when taken daily . `` While a vaccine or cure may one day end the HIV epidemic , PrEP is a powerful tool that has the potential to alter the course of the U.S. HIV epidemic today , '' Dr.Jonathan Mermin , director of the CDC 's National Center for HIV/AIDS , Viral Hepatitis , STD and TB Prevention , said in a statement . `` These guidelines represent an important step toward fully realizing the promise of PrEP . We should add to this momentum , working to ensure that PrEP is used by the right people , in the right way , in the right circumstances . '' According to the guidelines , those circumstances would be anyone who : . • has had sex without a condom ; . • is not infected with HIV but is in a sexual relationship with an HIV-infected partner ; . • is a gay or bisexual man who has had a sexually transmitted disease within the last six months and is not in a mutually exclusive relationship with a recently tested HIV-negative partner ; . • is a heterosexual man or woman who does not always use condoms when having sex with partners already at risk , and who is n't in a mutually exclusive relationship with a recently tested HIV-negative partner ; . or . • has injected drugs or shared drug paraphernalia in the past six months . In 2012 , the Food and Drug Administration approved Truvada , a pill that combines two antiretroviral drugs for the prevention of HIV . It was first approved in 2004 as an HIV treatment and is still the only FDA-approved medication for PrEP . Truvada is n't cheap . A month 's supply can cost you anywhere from $ 1,300 to $ 1,700 , according to Drugs.com . But insurance may cover the bill . To be effective , this pill must be taken every day . Dr. Anthony Fauci , an immunologist who has been at the forefront of HIV/AIDS research for decades , called it a highly effective approach to preventing the spread of the virus that causes AIDS . `` ( It 's ) one that benefits not only the individual patient at risk for HIV infection but also will help to reduce the number of new HIV infections across the United States , '' said Fauci , director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health . `` It should be used together with -- and complementary to -- condoms and not as a substitute for condoms . '' The new guidelines replace interim ones published two years ago ; they provide a comprehensive place where doctors and patients can find information on PrEP and come with a supplement that provides checklists for physicians , giving them step-by-step support for dealing with patients who might be considered for prophylactic treatment . `` PrEP is a new approach to HIV prevention that requires continuing collaboration between patients and providers , as effectiveness requires adherence to daily medication and regular medical visits for monitoring , counseling and testing , '' said Dr . Dawn K. Smith , an epidemiologist in CDC 's Division of HIV/AIDS Prevention who led the development of the guidelines . `` Individuals will have to decide with their doctor if PrEP is right for them , but for some , this may offer a much-needed strategy to help protect themselves from HIV infection . '' There are 1.1 million people in the United States living with HIV , according to the CDC . An estimated nearly one in six do not know they 're infected . Men who have sex with men are the hardest hit -- while they make up 2 % of the U.S. population , they account for 63 % of all new infections each year , according to the CDC . Heterosexuals make up 25 % of all new annual infections ; 9 % are injection drug users . `` HIV infection is preventable , yet every year we see some 50,000 new HIV infections in the United States , '' said Dr. Tom Frieden , the CDC 's director , in a statement . `` PrEP , used along with other prevention strategies , has the potential to help at-risk individuals protect themselves and reduce new HIV infections in the United States . ''
CDC recommends at-risk groups take Truvada daily to prevent HIV infection . Studies show pill can help reduce infection rates by more than 90 % when taken daily . Health experts say they hope this will `` alter the course of the U.S. HIV epidemic ''