Stanford University researchers have published a study on the cost effectiveness of a once-daily drug in reducing the risk of HIV infection through a prevention technique known as pre-exposure prophylaxis or PrEP. Using the pill in the general population of men who have sex with other men (MSM) would cost $495 billion over 20 years and $85 billion if only high risk MSM participated. Drug cost of Truvuda at $26 a day, physician fees, periodic monitoring of kidney function and regular testing for HIV and sexually transmitted diseases were considered. With these high costs, the researchers attempted to find the point with the highest payoff for a reasonable price. Results showed that 20 percent of the high-risk MSM participating would prevent 41,000 infections and cost about $16.6 billion. However, even this cost is high and may not be feasible in the current health care environment, so the team suggests further research on the effectiveness if the drug is used intermittently.