An optimized dried blood spot elution protocol for improved performance of the bioMérieux VIDAS HIV duo quick and Anti-HCV assay

Background Dried blood spots (DBS) offer a minimally invasive, low-cost specimen type that is well suited for HIV and hepatitis C virus (HCV) serosurveillance. Although most serological assays are intended for use with serum or plasma, many assays perform reliably with DBS. In a previous evaluation, the bioMérieux VIDAS HIV Duo Quick and Anti-HCV assays showed sensitivity and specificity ≤96% when applied to DBS. In this follow-up study, we aimed to improve the DBS elution protocol and assess whether these modifications improved the analytical performance of both assays. Methods We first examined HIV and HCV seronegative DBS under varying experimental conditions (buffer composition, number of punches, and elution parameters, including temperature and agitation) to evaluate their effects on background signal. Based on these experiments, we identified that elution in PBS containing 0.05% Tween 20 and 0.5% BSA, using a single 6 mm punch, and a 24-hour incubation at ambient temperature with agitation minimised background signal. We then analysed 494 DBS specimens from the Transitions study, a cross-sectional biobehavioural survey conducted in Dnipro, Ukraine, under these conditions. Performance metrics were calculated using the Avioq HIV-1 Microelisa System and Ortho HCV v3 ELISA Test System as the reference tests. Results Both VIDAS assays demonstrated excellent performance. Sensitivity and specificity were 100% for HIV Duo Quick and 99.03% and 100%, respectively, for Anti-HCV. Positive and negative predictive values exceeded 99%, and agreement with the reference tests was nearly perfect (κ ≥ 0.99). Conclusion These results support the use of both VIDAS assays for DBS-based serosurveillance.