Acceptability of an "on-demand" pre-exposure HIV prophylaxis trial among men who have sex with men living in France.

Although predictors of willingness to take daily, self-administered pre-exposure HIV prophylaxis (PrEP) for men who have sex with men (MSM) have been studied in the context of several PrEP trials internationally, little is known about MSM interested in participating in a trial on the use of PrEP on an "on -demand" basis, i.e., taking a first dose of combined tenofovir/emtricitabine a few hours before possible HIV sexual exposure and a second dose a few hours afterwards.