A Novel Wastewater-Based Serological Approach for Detecting Anti-SARS-CoV-2 IgM Antibodies

The emergence of Severe Acute Respiratory Syndrome - Coronavirus-2 (SARS-CoV-2) necessitate innovative surveillance strategies beyond conventional diagnostics. This study investigates the feasibility of wastewater-based epidemiology (WBE) for serological surveillance by detecting anti-SARS-CoV-2 membrane IgM antibodies using an optimized indirect enzyme-linked immunosorbent assay (ELISA) protocol. Wastewater samples (n = 10) from diverse localities across Nagpur city were processed using polyethylene glycol (PEG) precipitation to concentrate immunoglobulins. A checkerboard titration approach optimized assay conditions, identifying 5 ng of membrane peptide (LSYFLASFR), undiluted sample input, and a 1:5000 dilution of HRP-conjugated anti-human IgM as ideal. The assay demonstrated strong diagnostic performance with 80% sensitivity and 100% specificity, as validated by ROC curve analysis (AUC > 0.9, p = 0.0013). Real time PCR confirmed positive samples showed significantly elevated absorbance compared to negative controls. These findings suggest that antibody detection in wastewater is a robust, semi-quantitative, cost-effective and non-invasive tool for early community-level surveillance. This pilot study highlights the potential of serological WBE to complement traditional diagnostics, particularly in resource-limited settings and paves the way for scalable epidemiological monitoring of viral immunity at the population level.