A different HIV preventive vaccine developed by the Vaccine Research Center (VRC) at the U.S. National Institutes of Health (NIH) also uses a rAd5 virus vector. Although this vaccine, referred to as VRC Ad5, uses a rAd5 virus vector, it is structured and delivered differently than the MRK rAd5 vaccine. In two trials in Uganda it has shown no serious side effects. This study will perform safety follow-ups on participants in these two trials, RV 156A/WRAIR 1078A and RV 172/WRAIR 1218. Participants who received either the vaccine or the placebo will be recruited in order to compare health and HIV status.