Statistical Studies of Age - Specific HIV - Prevalence Data

The infectivity function is a function giving a measure of how infectious a given individual is t time units after becoming infected. Today, no feasible and ethically acceptable study design is known, which would lead to estimates of HIV-infection probability within steady heterosexual partnerships, using standard statistical methodology. In this paper a transmission model is used as a link between the infectivity function and data sets which already exist or can be generated with standard methods and moderate expenses. This model suggests that the distribution of HIV-infections by age and sex depends on the infectivity function as well as on age-dependent patterns of sexual partner choice. Application of the model requires populationbased data of age-specific HIV-incidences in men and women of the general heterosexual population. At present, the only known data set suitable for this purpose is a set of HIV-test results from a sample of 8690 Colombian women in pregnancy who attended prenatal care. The prevalence of HIV was 0.33% in the group of 12-24 years, but only 0.16% in the group of 25-34 years. The model can explain this strange result. A data set of age-specific HIV-prevalences in heterosexual Colombian men would be useful, but is not known. Therefore, further research and data collecting is required in order to arrive at well founded conclusions.