SARS-CoV-2 Transmission in Alberta, British Columbia, and Ontario, Canada, January 1-July 6, 2020

Objective To investigate COVID-19 epidemiology in Alberta, British Columbia and Ontario, Canada. Methods We calculated the incidence rate ratio (January 1—July 6, 2020) between the 3 provinces, and estimated time-varying reproduction number, R t , starting from March 1, using EpiEstim package in R. Results Using British Columbia as a reference, the incidence rate ratios in Alberta and Ontario are 3.1 and 4.3 among females, and 3.4 and 4.0 among males. In Ontario, R t fluctuated ~1 in March, reached values >1 in early and mid-April, then dropped <1 in late April and early May. R t rose to ~1 in mid-May and then remained <1 from late May through early July. In British Columbia, R t dropped <1 in early April, but it increased towards the end of April. R t 1 in March; R t dropped in early April and rose again in late April. In much of May, R t <1, but R t increases in early June and fluctuates ~1 since mid-June. Conclusions R t wavering around 1.0 indicated that three provinces of Canada have managed to achieve limited onward transmission of SARS-CoV-2 as of early July 2020.