There is no expection that postexposure treatment will have a major impact on the epidemic in the United States. Only isolated cases will be candidates for postexposure treatment, and that in some cases postexposure treatment will not be effective. Data on the efficacy of postexposure treatment is limited, according to CDC officials, but a several human studies have demonstrated that postexposure treatment can markedly reduce the risk for contracting HIV in some cases. Studies show that animals successfully treated postexposure were given anti-HIV drugs early and for several weeks. PMPA has protected some nonhuman primates from infection for more than a year now, after it was given within 24 hours of exposure and administered for four weeks.
Studies suggest that animals treated for lesser periods of time are more likely to become infected.
The reverse transcriptase inhibitor nevirapine apparently aborted HIV infection in chimpanzees, according to Dr. Peter Grob of Boehringer Ingelheim. Chimpanzees treated with a loading dose of the drug, followed by 10-20 days of additional therapy, showed some serologic evidence of infection but no detectable viral RNA, Dr. Grob said, and the animals showed no evidence of latent infection. The CDC expects to hold an additional meeting on postexposure treatment with its consultants later this year, and hopes to have draft guidelines available by year's end. Final recommendations may be ready next year.