Vaccinia scars associated with improved survival among adults in rural Guinea-Bissau

Abstract

Background. In urban Guinea-Bissau, adults with a vaccinia scar had better survival but also a higher prevalence of HIV-2 infection. We therefore investigated the association between vaccinia scar and survival and HIV infection in a rural area of Guinea-Bissau. Methodology/Principal Findings. In connection with a study of HIV in rural Guinea-Bissau, we assessed vaccinia and BCG scars in 193 HIV-1 or HIV-2 infected and 174 uninfected participants. Mortality was assessed after 2 1/2-3 years of follow-up. The analyses were adjusted for age, sex, village, and HIV status. The prevalence of vaccinia scar was associated with age, village, and HIV-2 status but not with sex and schooling. Compared with individuals without any scar, individuals with a vaccinia scar had better survival (mortality rate ratio (MR) = 0.22 (95% Cl 0.08-0.61)), the MR being 0.19 (95% Cl 0.06-0.57) for women and 0.40 (95% Cl 0.04-3.74) for men. Estimates were similar for HIV-2 infected and HIV-1 and HIV-2 uninfected individuals. The HIV-2 prevalence was higher among individuals with a vaccinia scar compared to individuals without a vaccinia scar (RR = 1.57 (95% Cl 1.02-2.36)). Conclusion. The present study supports the hypothesis that vaccinia vaccination may have a non-specific beneficial effect on adult survival. © 2006 Jensen et al.