Background: Population viral load (PVL) reflects antiretroviral therapy (ART) program effectiveness and transmission risk in a population. Using nationally representative data from household surveys conducted in Zimbabwe, Malawi and Zambia in 2015-16, we examined the association between PVL and viral load suppression (VLS) and the probability of at least one recent HIV-1 infection in the surveys'' smallest geographic sampling unit, an enumeration area (EA).
Methods: Viral load (VL) and limiting-antigen avidity enzyme immunoassay (LAg-Avidity EIA) testing were performed on all HIV-1 positive (+) samples. Recent HIV cases were defined by World Health Organization criteria (LAg-Avidity EIA < 1.5 ODn and HIV RNA > 1000 c/mL), and VLS as HIV RNA < 1000 c/mL. PVL was defined as the arithmetic mean of log10 HIV RNA of HIV+ individuals in the EA, and ART coverage as prevalence of self-reported current ART use. We used logistic regression adjusted for EA-level variables, e.g., HIV prevalence, population size and mean age of the female population, to estimate the probability of one recent HIV-1 infection.
Results: Among 1,510 EAs across the three surveys, a total of 58,366 adults aged 15-59 years resided in 1,374 (91%) EAs that had at least one HIV+ adult consenting to an interview and blood draw. Among the 1,374 EAs, 92.65%, 6.99% and 0.04% had 0, 1 and 2 recent HIV-1 cases, respectively. Mean VLS prevalence across these EAs was 63.5% (95% confidence intervals (CI) 62-65%).
In multivariable analysis, PVL, particularly among those unaware of their HIV+ status, was associated with a recent HIV-1 case in that EA (adjusted odds ratio [AOR]: 1.44, 95% CI 1.22-1.70, p < 0.001). VLS prevalence was inversely correlated with recent infections (AOR: 0.17, 95% CI 0.08-0.37, p < 0.001). On average, every 1% increase in VLS in an EA decreased the predicted probability of one recent infection by 8%.
Conclusions: We found a strong association between PVL and VLS prevalence with recent HIV-1 infection at the EA level in three southern African countries with generalized HIV epidemics. These results suggest expanding and maintaining high levels of VLS may be key to HIV epidemic control in these three countries.