Evidence
Strong evidence suggests that a short course of ARVs started within 72 h after exposure effectively reduces HIV transmission rates following needle stick exposure to HIV-infected blood. This comes largely from a single-case control study involving health care workers from France, UK and USA that revealed strong inverse associations between the likelihood of HIV infection following a needlestick injury and the postexposure use of zidovudine. However, data available from animal transmission models, perinatal clinical trials, studies of health-care workers receiving prophylaxis after occupational exposures, and observational studies indicate that PEP may reduce the risk of HIV infection after nonoccupational exposures as well.