Effectiveness of post-exposure prophylaxis

  • PEP has been shown to be effective in animal studies.
  • An observational study in Brazil calculated that PEP reduced the seroconversion rate in gay men by 83%.
  • Some PEP failures have been attributed to people taking further sexual risks while on PEP.

A number of studies have examined the effectiveness of post-exposure prophylaxis (PEP) in animal models and in humans. Studies in humans have largely concentrated on ‘occupational exposure’, usually of healthcare workers. However, more recent findings have looked at infection rates following exposure through non-occupational means, such as unprotected sex.

It is not possible to carry out randomised trials comparing PEP to no treatment in humans, as this would involve denying some exposed patients treatment. Consequently, almost all of the evidence on the effectiveness of PEP in humans comes from observational studies.

Evidence for the effectiveness of PEP has been demonstrated by prevention of mother-to-child transmission of HIV by short courses of antiretroviral drugs in newborns. This is discussed in Mother-to-child transmission.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.