Giving a daily preventive dose of an aids-fighting drug to high-risk men could be beneficial but the costs of doing so would run in to billions of US dollars says a University of Stanford Study.

Researchers have been trying to find feasible way of reducing HIV infection among high-risk men who have sex with men (MSM).

The study estimates that giving a preventive dose of the drug to MSM’s would cost $495 billion in over 20 years in terms of the cost of drug and healthcare.

The study is published in Annals of Internal Medicine.

The study authors write that initiating PrEP in 20% of the overall MSM population would cost $172,091 per quality adjusted life-year (QALY) gained. If prophylaxis were targeted to high-risk MSM, however, the QALY cost would be approximately $50,000.

Another study, published in 2010 in New England School of Medicine, had found that antiretroviral drugs were effective as pre-exposure prophylaxis (PrEP) in preventing HIV infection in MSM by 44%.

According to CDC, “Gay, bisexual, and other men who have sex with men (MSM) represent approximately 2%of the U.S population, yet are the population most severely affected by HIV and are the only risk group in which new HIV infections have been increasing steadily since early 1990’s.”

“Use in high-risk men who have sex with men would prove substantial health benefits at a lower cost, although the budgetary effect would still be sizeable,” Jessie Juusola, a PhD candidate at Stanford wrote in the study.

CDC had issued a primary guideline last year that only high-risk gay and bisexual men should use a daily AIDS pill to protect themselves from the virus.

An estimated 1.2 million Americans have HIV according to CDC.

An FDA advisory panel is expected to consider in mid-May whether to allow the use of a drug as a way to prevent HIV infection in healthy people.

According to Reuters, Gilead is seeking permission for Truvada - a combination of its HIV drugs Emtriva, also known as emtricitabine, and Viread, or tenofofir - to be used as a form of pre-exposure prophylaxis.

Pre-exposure prophylaxis or PrEP is a part of comprehensive HIV prevention services in which HIV negative people who are at high risk, take antiretroviral medication to prevent an HIV infection.