We estimated COVID-19 transmission potential and case burden by variant type in Alberta, British Columbia, and Ontario, Canada, during January 23, 2020–January 27, 2022; we also estimated the effectiveness of public health interventions to reduce transmission. We estimated time-varying reproduction number (R_t) over 7-day sliding windows and nonoverlapping time-windows determined by timing of policy changes. We calculated incidence rate ratios (IRRs) for each variant and compared rates to determine differences in burden among provinces. R_t corresponding with emergence of the Delta variant increased in all 3 provinces; British Columbia had the largest increase, 43.85% (95% credible interval [CrI] 40.71%–46.84%). Across the study period, IRR was highest for Omicron (8.74 [95% CrI 8.71–8.77]) and burden highest in Alberta (IRR 1.80 [95% CrI 1.79–1.81]). Initiating public health interventions was associated with lower R_t and relaxing restrictions and emergence of new variants associated with increases in R_t.

我们估计了2020年1月23日至2022年1月27日期间阿尔伯塔省、不列颠哥伦比亚省和加拿大安大略省按变体类型划分的COVID-19传播潜力和病例负担；我们还评估了公共卫生干预措施在减少传播方面的有效性。我们估计了7 天滑动窗口和由政策变化时间决定的非重叠时间窗口的随时间变化的再生数 (R _t )。我们计算了每种变体的发病率比（IRR）并比较了发病率以确定各省之间负担的差异。与 Delta 变种的出现相对应的Rt在所有 3 个省份_均有所增加；不列颠哥伦比亚省增幅最大，为 43.85%（95% 可信区间 [CrI] 40.71%–46.84%）。在整个研究期间，Omicron 的 IRR 最高（8.74 [95% CrI 8.71–8.77]），艾伯塔省的负担最高（IRR 1.80 [95% CrI 1.79–1.81]）。启动公共卫生干预措施与较低的 R _{t和放宽限制以及与 R t}增加相关的新变体的出现有关。