Long-Term Persistence of Vaccine-Induced HIV Seropositivity in Healthy

Objectives: To assess the long-term serological impact of HIV preventive vaccine trial participation, vaccine- induced HIV seropositivity (VISP) was evaluated and related factors were investigated. The anti-HIV antibody reactivity ratio distribution was estimated. Methods: ANRS COHVAC is an open national prospective multicentre cohort study including healthy volunteers who received at least one dose of vaccine candidate of ANRS HIV preventive vaccine trials since 1992. VISP was studied in a cross-sectional study at the time of the cohort's initial visit, starting in 2008. Anti-HIV antibody detection was performed using the ABBOTT ARCHITECT® HIV Ag/Ac Combo Enzyme Immunoassay (EIA) in a centralized laboratory. A ratio greater than or equal to 1 was considered to define HIV seropositivity. Results: 293 participants were evaluated for a median period of 6 years (range: 2-18 years) after their inclusion in vaccine preventive trials. The frequency of VISP was estimated at 7.2% (21 out of 293) for all volunteers, and 69.0% (20 out of 29) for volunteers who received recombinant HIV-1 envelope protein, after a median period of 16.6 years after immunization (range: 16.3-18.4). The ARCHITECT test ratio among positive volunteers was low, with a median of 3.02 (range: 1.02 -14.04). Conclusion: Healthy volunteers should be informed of possible VISP persistence for nearly 17 years, following HIV envelope vaccination inducing antibody responses. A single, routine serology test is unable to differentiate between VISP and a recent HIV infection. The combination of different technologies, applicable to resource-limited settings, is needed to distinguish vaccine-induced seropositivity from an HIV infection.