Objective: To describe transmission vulnerability for acquiring HIV infection among the Brazilian population aged 15-54 years.
Design: A population-based survey.
Methods: Sampling was stratified by geographical region. A total of 6006 interviews were conducted. Indicators of knowledge and sexual practices and the relative sizes of the vulnerable subgroups were estimated. Logistic regression analysis was used to determine the main factors associated with safe sex practices.
Results: Regarding knowledge indicators in the age group 15-24 years, a high percentage (91%) spontaneously cited sexual intercourse as a form of HIV transmission, and 62% had correct knowledge of the modes of HIV transmission (five correct items). The proportion of consistent condom use with casual partners was 52%, increasing to 59% in the youngest age group. Higher proportions of inconsistent condom use with any kind of partner were found among women and among the poorest. A multiplicity of sexual partners, low socio-economic status and cocaine use were important predictors of unprotected sex among men living without a companion. Among individuals aged 15-49 years, 0.2% currently inject cocaine, 4.6% of the men paid for sex at least once over the past year and 1.0% of the women were paid in exchange for sex. Among sexually active men of the same age group, 3.5% reported sexual relations with other men.
Conclusion: Besides the need to establish the role exercised by the vulnerable subgroups in the HIV transmission dynamics, results indicate that it is necessary to investigate unsafe sexual practices further among the poorer sectors of society.