Comparison of HIV Incidence in the Zimbabwe Population-Based HIV Impact Assessment Survey (2015–2016) with Modeled Estimates: Progress Toward Epidemic Control

Abstract

Background: Zimbabwe conducted a Population-Based HIV Impact Assessment (ZIMPHIA) cross-sectional survey, October 2015 and August 2016 to determine progress toward epidemic control. Methods: Of 25,131 eligible adults 15–64 years, 20,577 (81.8%) consented to face-to-face questionnaire and biomarker testing in this nationally representative household survey. Home-based rapid HIV testing was performed using Determine, First Response and Stat-Pak as the tie-breaker. HIV-positive tests were confirmed in a laboratory using Geenius HIV-1/2, viral load (VL) was measured using Roche TaqMan and BioMerieux NucliSENS. Recency of infection was tested using Sedia HIV-1 Limiting Antigen-Avidity (LAg). Presence of antiretroviral (ARV) drugs was detected using HPLC/MS. The recent infection testing algorithm (RITA) included LAg-Avidity Enzyme-immuno-assay (EIA (normalised-optical density (ODn<=1.5), viral load≥1000 copies/mL, and absence of antiretroviral drugs. Weighted annual HIV incidence was compared to UNAIDS Spectrum models estimates. Results: Overall, 26 of 2,901 HIV-seropositive individuals had a recent infection (men, 8; women, 18). Overall weighted annual incidence among persons 15–64 years was 0.42% (95% confidence interval [CI]: 0.25–0.59) and 0.44% (95% CI: 0.25–0.62) for 15–49 years, similar to 2016 Spectrum model estimate (0.54%; 95% CI: 0.49–0.66) for this age group. Among persons aged 15–49 years, HIV prevalence was 13.35 % (95% CI: 12.71-14.02), estimated HIV-positive individuals were 968,951 (95% CI: 911,473–1,026,430), of these, 41,911 (95% CI: 37,412–44,787) were annual-new infections and this was similar to 2016 Spectrum estimates. Conclusion: The observed HIV incidence in ZIMPHIA 2015/16 validated the 2016 Spectrum estimates and Zimbabwe’s progress toward epidemic control.