Declining Age at HIV Infection in the United States

To the Editor: Age-specific data on the seroincidence of the human immunodeficiency virus (HIV) are difficult to obtain. Although several studies in special populations have shown relatively high seroprevalence and seroincidence in younger people, trends in the general population of the United States remain unknown. We and others1–3 have reported “back-calculation” methods to link data on the incidence of AIDS to data on the incidence of HIV infection, using knowledge of the distribution of the time from HIV infection (technically, seroconversion) to the onset of AIDS, which is known as the incubation distribution. By modeling the age-specific incidence of . . .