Implications of increased infectivity in early-stage HIV infection. Application of a Bernoulli-process model of HIV transmission.

Recent reports suggest that the infectivity of sexually transmitted HIV (i.e., the probability of transmission on a single sexual contact) may be up to 1,000 times greater during the first few months of infection than during the long asymptomatic period that precedes the development of AIDS. Assuming the validity of this estimate, a simple Bernoulli-process model of HIV transmission indicates that, in some cases, the expected number of secondary infections is greater for the brief period of primary infection than for the much longer asymptomatic phase. The implications of these findings for current HIV/AIDS prevention practices are analyzed with particular attention to the role of condom use in preventing HIV transmission.