%0 Journal Article
%T Omicron COVID-19 Case Estimates Based on Previous SARS-CoV-2 Wastewater Load, Regional Municipality of Peel, Ontario, Canada.
%A Cheng L
%A Dhiyebi HA
%A Varia M
%A Atanas K
%A Srikanthan N
%A Hayat S
%A Ikert H
%A Fuzzen M
%A Sing-Judge C
%A Badlani Y
%A Zeeb E
%A Bragg LM
%A Delatolla R
%A Giesy JP
%A Gilliland E
%A Servos MR
%J Emerg Infect Dis
%V 29
%N 8
%D 2023 08 28
%M 37379513
%F 16.126
%R 10.3201/eid2908.221580
%X We determined correlations between SARS-CoV-2 load in untreated water and COVID-19 cases and patient hospitalizations before the Omicron variant (September 2020-November 2021) at 2 wastewater treatment plants in the Regional Municipality of Peel, Ontario, Canada. Using pre-Omicron correlations, we estimated incident COVID-19 cases during Omicron outbreaks (November 2021-June 2022). The strongest correlation between wastewater SARS-CoV-2 load and COVID-19 cases occurred 1 day after sampling (r = 0.911). The strongest correlation between wastewater load and COVID-19 patient hospitalizations occurred 4 days after sampling (r = 0.819). At the peak of the Omicron BA.2 outbreak in April 2022, reported COVID-19 cases were underestimated 19-fold because of changes in clinical testing. Wastewater data provided information for local decision-making and are a useful component of COVID-19 surveillance systems.