PEP should be initiated as soon as possible, preferably within 72 hours after a possible exposure to the HIV.30 This recommendation is based on evidence that following primary exposure systemic infection does not occur immediately, leaving a brief window of opportunity during which PEP might limit the proliferation of HIV in initial target cells or lymph nodes. In a retrospective case-control study of HCP, PEP with zidovudine reduced the risk of HIV infection by approximately 81%.29
The U.S. Public Health Service no longer recommends that the severity of exposure be used to determine the number of drugs to be offered in an HIV PEP regimen. A basic 4 week PEP regimen containing 3 (or more) antiretroviral drugs is now routinely prescribed following all occupational exposures. The recommended PEP regimen include two NRTIs plus an INSTI, or a NNRTI, or a PI with a pharmacokinetic booster such as cobicistat or ritonavir.30
