Background: Adolescent girls and Young women (AGYW) in South Africa bear a disproportionate burden of HIV. Community mobilization (CM), defined as community members taking collective action to achieve a common goal, has been found to be associated with increased HIV testing and condom use and has been called a ''critical enabler'' for addressing the HIV epidemic. However, limited research has explored whether CM, or living in a mobilized community, is associated with HIV incidence among AGYW.
Methods: We conducted a longitudinal analysis among 2,533 AGYW (ages 13-21) enrolled in the HPTN 068 cohort in the Agincourt Health and Demographic Surveillance System, South Africa. This analysis includes all participants who lived in 28 villages where we also conducted cross-sectional, population-based surveys among 18-35 year old residents in 2012 and 2014. HPTN 068 participants completed up to five annual visits, receiving an HIV test at each visit (2011-2016). Household-level data were collected from the parent/guardian of each AGYW and census data is collected annually. Mean village-level CM scores were created using a validated CM measure composed of seven components (community social cohesion, social control, collective consciousness, shared concerns, organizations and networks, leadership, and collective action). We used pooled generalized estimating equations with a Poisson distribution to estimate the risk ratios (RR) of incident HIV infection, adjusting for the village-level clustering and key covariates.
Results: There were 177 incident infections over the follow-up period. For every standard deviation increase in village-level CM there was a 14% reduction in HIV incidence (RR: 0.86, 95% CI: 0.74, 0.99, p< 0.05) after adjusting for age, time enrolled in the 068 cohort, education, household assets, and a collated measure of community characteristics (mean community education, proportion of community in highest SES quintile, proportion permanent residents).
Conclusions: These results support that living in a mobilized community, where communities work collectively and organize to address community welfare, can reduce AGYW''s risk of HIV acquisition. Community mobilization efforts may be an important component in HIV prevention programs for AGYW.

CharacteristicsUnadjusted RR (95% CI)Adjusted aRR (95% CI)
Age at baseline1.21 (1.11, 1.31)***1.18 (1.11, 1.26)***
Time in study (2nd follow-up)1.27 (0.74, 2.18)1.08 (0.61, 1.93)
Time in study (3rd follow-up)1.68 (0.95, 2.96)1.55 (0.93, 2.57)
Time in study (4th follow-up)4.17 (2.87, 6.05)***2.98 (2.01, 4.41)***
Enrolled in school or graduated high school0.23 (0.14, 0.38)***0.52 (0.33, 0.82)**
Household assets1.02 (1.00, 1.05)*1.01 (0.98, 1.03)
Community mobilization0.79 (0.67, 0.92)**0.86 (0.74, 0.99)*
Community characteristics1.12 (1.03, 1.22)**1.08 (0.99, 1.17)
* p<.05; ** p<.01; ***p<0.001
[Unadjusted and Adjusted Risk Ratios (RR) of incident HIV among young women enrolled in HPTN 068 (N=2,533)]