RESUMO
BACKGROUND: HIV/AIDS continues to be a global health problem. With currently no cure, it is critical to get an effective vaccine to add to the arsenal of prevention and treatment tools. HIV Exposed Sero-Negative (HESN) individuals were enrolled and followed for 2 years. METHODS: A prospective observational cohort study to enroll HESN volunteers and their partners was developed with a 2-year follow up. This was a vaccine preparedness study and designed as a Phase IIb trial. We provided counseling, lab testing and conducted medical examinations for all enrollees. RESULTS: A total of 534 HESN were enrolled with 48 % (256) females and 52 % (278) males, a mean age of 37 ± 9 years. Three female HESN enrollees seroconverted giving this cohort a HIV incidence rate [95 % coefficient interval (CI)] of 3.2 (2.3-4.2) per 100,000 person-months of observation. Baseline analysis showed that female HESN are 24 % more likely to have their spouse consistently use condoms (RR 1.24; p = 0.04); 16 % more likely to have HIV+ partners with detectable viral load (RR 1.16, p = 0.03) and 28 % more likely that their HIV+ partners has a CD4 count less than 350cells/µl (RR 1.28, p = 0.03) when compared to male HESN. CONCLUSIONS: Our findings suggest that female HESN are more at risk of HIV acquisition due the low CD4 counts and detectable viral load among their HIV+ spouses. Moreover, we provide additional information on incidence and risk factors among naturally exposed persons, which might impact biomedical prevention research and immune responses to HIV vaccines.