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Volume 30, Number 5—May 2024
Research

SARS-CoV-2 Transmission in Alberta, British Columbia, and Ontario, Canada, January 2020–January 2022

Aubrey D. Kehoe1, Arshpreet Kaur Mallhi1, Charles R. Barton2, Hunter M. Martin2, Christopher M. Turner2, Xinyi Hua, Kin On Kwok, Gerardo Chowell, and Isaac Chun-Hai FungComments to Author 
Author affiliations: Georgia Southern University Jiann-Ping Hsu College of Public Health, Statesboro, Georgia, USA (A.D. Kehoe, A.K. Mallhi, C.R. Barton, H.M. Martin, C.M. Turner, X. Hua, I.C.-H. Fung); Chinese University of Hong Kong JC School of Public Health and Primary Care, Hong Kong (K.O. Kwok); Georgia State University School of Public Health, Atlanta, Georgia, USA (G. Chowell)

Main Article

Figure 1

Daily incident COVID-19 case count and 7-day moving average Rt, by date of infection and policy-change Rt or new variants by initiation dates, Ontario, Canada, January 23, 2020–January 27, 2022. Dates are assumed infection dates (i.e., report date minus 9 days); red dotted lines in panels C and D indicate Rt = 1. A, B) Incident case count by date of infection for all variants combined (A) and by variant type (B). Colors indicate COVID-19 variants: purple, wild-type; red, Alpha; green, Delta; blue, Omicron; and gray, other variants. C) Seven-day moving average Rt by date of infection. D) Policy-change Rt. Policy changes or detection of new variations by dates of initiation: A, school closure (March 14, 2020); B, recommendation for use of face masks (April 7, 2020); C, phased school reopening (September 8, 2020); D, priority populations vaccination rollout (December 18, 2020); E, partial school reopening (January 8, 2021); F, school closure (April 12, 2021); G, increase in cases because of Delta COVID-19 variant (July 1, 2021); H, requirement of vaccination for federal workers (August 13, 2021); I, increase in cases because of the Omicron COVID-19 variant (November 25, 2021).

Figure 1. Daily incident COVID-19 case count and 7-day moving average Rt, by date of infection and policy-change Rt or new variants by initiation dates, Ontario, Canada, January 23, 2020–January 27, 2022. Dates are assumed infection dates (i.e., report date minus 9 days); red dotted lines in panels C and D indicate Rt = 1. A, B) Incident case count by date of infection for all variants combined (A) and by variant type (B). Colors indicate COVID-19 variants: purple, wild-type; red, Alpha; green, Delta; blue, Omicron; and gray, other variants. C) Seven-day moving average Rt by date of infection. D) Policy-change Rt. Policy changes or detection of new variations by dates of initiation: A, school closure (March 14, 2020); B, recommendation for use of face masks (April 7, 2020); C, phased school reopening (September 8, 2020); D, priority populations vaccination rollout (December 18, 2020); E, partial school reopening (January 8, 2021); F, school closure (April 12, 2021); G, increase in cases because of Delta COVID-19 variant (July 1, 2021); H, requirement of vaccination for federal workers (August 13, 2021); I, increase in cases because of the Omicron COVID-19 variant (November 25, 2021).

Main Article

1These first authors contributed equally to this article.

2These second authors contributed equally to this article.

Page created: February 29, 2024
Page updated: April 25, 2024
Page reviewed: April 25, 2024
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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