How does PrEP stop HIV with condomless sex?

PrEP is a pill that is absorbed in our digestive system. After some metabolism, the active compound is absorbed in our bloodstream.

Many of HIV infections occur due to the exposure of mucosal areas to the virus during Sex. The mucosa is exposed to high viral loads, and the virus reaches the bloodstream.  Afterwards, the virus infects the CD4 lymphocytes.

If our blood at the mucosal areas has high concentrations of PrEP, the virus won’t be able to infect the CD4 cells in our blood. Therefore, the infection won’t be established.