The average risk of transmission of the human immunodeficiency
virus (HIV) to a health care worker after percutaneous exposure to
HIV-infected blood has been estimated as 0.3 percent. However, the
factors that influence this risk have not been determined, and the
efficacy of postexposure prophylaxis with antiretroviral drugs have
not been clinically evaluated. If postexposure prophylaxis is
effective, it would offer an entirely new strategy for preventing
HIV transmission in nonoccupational settings as a supplement to the
preferred strategy of...