Understanding Transmission and Infections of Respiratory Syncytial Virus through Wastewater-Based Epidemiology †

Abstract

Wastewater-based epidemiology (WBE) is an effective tool for tracking community circulation of respiratory viruses. We address a scientific gap that takes measured wastewater viral load of Respiratory Syncytial Virus (RSV) and estimate the effective reproduction number and the number of infections in the population. We advocate a modular approach to the analysis. We first estimate the trend and current level of the RSV viral load and quantify the uncertainty. These estimates become input for our Bayesian renewal model for both the infection rate and the number of infected individuals. The modular approach simplifies the analysis pipeline while maintaining scientific integrity. Further, the modular approach supports translation to other viruses by using disease-specific models for estimated transmission and cases in the second phase of the analysis. 1 INTRODUCTION. Wastewater-based epidemiology (WBE) has become an essential tool for monitoring infectious diseases at the population level. By analyzing viral genetic material in wastewater, WBE offers a noninvasive and cost-effective way to detect early signs of community spread, regardless of whether individuals seek medical care or undergo clinical testing. 1 For respiratory syncytial virus (RSV), a leading cause of severe respiratory illness in infants, older adults, and immunocompromised people, clinical surveillance faces challenges from underreporting and delays in reporting. Many RSV cases are managed at home without hospitalization, so clinical records do not fully reflect community transmission. Fortunately, RSV can be detected in wastewater. 2 In a comprehensive study of 176 sites during the 2022-2023 RSV season, Zulli et al. 3 observed that RSV RNA concentrations at state and national levels were linked to infection positivity and hospitalization rates. Allen et al. 4 detail the implementation of a WBE approach in Northern Ireland to track RSV community transmission over the 2021 and 2022 seasons, correlating wastewater RSV levels with clinical cases. Through sequencing and phylogenetic analysis, they compared RSV A and B