Wastewater-based epidemiology for SARS-CoV-2 and other respiratory viruses: A systematic review of sampling strategies and analytical workflows

Wastewater-based epidemiology (WBE) has emerged as a critical surveillance tool for respiratory viruses. This study systematically reviewed 416 studies across 56 countries evaluating sampling strategies and analytical workflows for 11 respiratory viruses. SARS-CoV-2 dominated research (96.6 %), followed by influenza A (5.0 %) and human adenovirus (4.3 %). Strong geographic disparities were evident: North America and Europe contributed 65.1 % of studies, while Africa and low-income regions remained underrepresented. Sampling strategies varied substantially: influent wastewater was predominantly sampled (96.2 %) from treatment plants (78.8 %), using 1000–5000 mL volumes (32.2 %), with composite sampling preferred over grab sampling (65.6 % versus 37.3 %), conducted weekly (29.3 %). Analytically, mixed concentration methods (28.8 %) and polyethylene glycol (PEG) precipitation (24.8 %) dominated viral concentration. Silica column-based extraction (55.3 %) and reverse transcription quantitative polymerase chain reaction (RT-qPCR) detection (87.3 %) were most common. The inconsistency observed across WBE workflows, including 22.4 % of studies not reporting sampling frequency, 37.5 % not reporting sample volume, and 4.3 % not specifying concentration methods, underpins our recommendation for standardized reporting protocols. Adopting consistent and transparent methodologies will improve data comparability, strengthen public health response capacity, and guide the development of future wastewater surveillance efforts for respiratory viruses. • Systematic review of 416 WBE studies shows high methodological diversity. • Influent wastewater (96.2 %) and composite sampling (65.6 %) most common. • RT-qPCR dominates detection (85.8 %); PEG precipitation widely applied. • Geographic disparity: 65.1 % studies from developed regions, 7.7 % from LMICs. • Standardized protocols and transparent reporting needed for comparability.