Wikipedia
IPERGAY
IPERGAY was a French clinical trial of pre-exposure prophylaxis (PrEP) in sexually active gay men in a community setting. It demonstrated 86% effectiveness in preventing HIV transmission.
The study was published in December 2015 looking at an alternative strategy of "on-demand" PrEP where Truvada was taken 2–24 hours before sexual activity and only continued for 2 days afterwards. In a population of 400 gay men in France and Canada at high risk for HIV, this strategy led to an 86% drop in HIV infections over the average 9 month follow-up of the study. As of December 2015, non-continuous PrEP methods have not been endorsed by WHO or national guidelines.