Characterization of New HIV Infections among Adults ≥45 Years—New York City, North Carolina, San Francisco, 2011–2013

Background While HIV prevention activities are often focused on younger people, older people can also be at risk for HIV infection. We aimed to characterize HIV transmission in older adults. Methods The STOP study was a multi-site prospective study of persons with acute HIV infection (AHI) from 2011 to 2013. Older adults were defined as ≥45 years and younger persons were 13–44 years. AHI was defined by a negative rapid test but a reactive antigen/antibody or HIV RNA test. We performed bivariate analysis using Pearson’s chi-square and odds ratios to examine associations between older age and transmission characteristics. Among persons with HIV-1 polymerase (pol) sequences, transmission linkages were inferred when the genetic distance between sequences was Results Among 86,836 participants (median age, 29 years; 75.0% male; 51.8% MSM), HIV infection was diagnosed in 176 (1.46%) of 12,036 older adults compared with 1,150 (1.53%) of 74,800 younger people (P = 0.56). Among HIV-infected persons, AHI was diagnosed in similar proportions of older and younger people (13.1% vs. 12.6%; P = 0.86). Among HIV-infected persons who participated in partner notification (n = 1,326), older adults were less likely to report meeting a sex partner online (11.3% vs. 26.9%; OR 0.52, 95% CI = 0.35–0.78) and were less likely to name ≥2 sex partners (31.5% vs. 46.8%; OR = 0.28, 95% CI = 0.15–0.53) compared with younger people. Among HIV-infected persons with HIV-1 pol sequences (n = 537), similar proportions of older and younger people had viruses that genetically linked with another study participant (15.9% vs. 23.5%; OR 0.62, 95% CI 0.31–1.22) (Figure). Conclusion In this study, older adults had a similar frequency of newly diagnosed HIV infection, acute infection, and genetic linkage compared with younger people, suggesting that increased HIV prevention efforts may be needed in this population. Disclosures All authors: No reported disclosures.