SARS-CoV-2 titers in wastewater are higher than expected from clinically confirmed cases

Fuqing Wu; Amy Xiao; Jianbo Zhang; Xiaoqiong Gu; Wei Lin Lee; Kathryn Kauffman; William Hanage; Mariana Matus; Newsha Ghaeli; Noriko Endo; Claire Duvallet; Katya Moniz; Timothy Erickson; Peter Chai; Janelle Thompson; Eric Alm

To discriminate between these possibilities, additional catchments of different sizes should be tested. By integrating data on the presence or absence of viral particles across catchments of varying size within the same geographic region, it may be possible to estimate disease prevalence independent from knowing the average viral titer in infected stool. For example, if disease prevalence is 1 in 10,000, then approximately 50% of catchment areas representing ~7,000 individuals would be positive (although cases may cluster within households, so additional experiments or modeling would be needed to derive precise numbers). These experiments require sampling upstream areas in the sewage system, using specialized equipment to capture . CC-BY 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Methods. 24 hour composite samples of raw sewage were taken from the wastewater treatment facility influent, and pasteurized at 60C for 90 min to inactivate virus. Raw sewage was then filtered through a 0.2 um membrane (Millipore Sigma) to remove bacterial cells and debris. Filters were discarded, as initial tests revealed little to no viral RNA on filters. 4 g of Polyethylene glycol 8000 (8% w/v, Millipore Sigma) and 0.9 g NaCl (0.3 M, Millipore Sigma) was then added to 40 mL filtrate, and centrifuged at . CC-BY 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.