Use of Varied Screening Risk Criteria and HIV Incidence in Phase 1 and 2 HIV Vaccine Trials in South Africa.

Many early phase HIV prevention studies define HIV risk-related eligibility criteria. We conducted a retrospective review of HIV Vaccine Trials Network (HVTN) Phase 1 and 2 HIV vaccine clinical trials completed in South Africa from 2003 to 2020, evaluating HIV incidence by protocol-defined risk criteria. Comparisons between groups controlled for age, gender and year of trial initiation. Across 12 trials, 1 did not specify risk criteria, and 11 specified various low risk criteria thematically categorized under sexual behaviors, clinical characteristics, and/or drug use behavior. Of the 11 trials, 6 used low sexual risk eligibility criteria standardized by the HVTN in 2009. Of the 1249 participants, median age 23.0 years, 66% were enrolled with the HVTN 2009 standardized low risk criteria, 15% using other sets of low risk criteria, and 19% using no risk criteria. Compared with the standardized low risk criteria group [2.3], HIV incidence per 100 person-years was significantly higher in the non-standardized low risk criteria group [5.0] and in the no risk criteria group [4.8]. In South Africa, cohorts with low HIV incidence can be identified primarily through sexual behavior and clinical characteristics.