Department of Community Health and Epidemiology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
Saskatchewan Population Health and Evaluation Research Unit, Saskatoon, SK, Canada.
JMIR Public Health Surveill. 2022 May 31;8(5):e31968. doi: 10.2196/31968.
There is mounting evidence that the third wave of COVID-19 incidence is declining, yet variants of concern (VOCs) continue to present public health challenges in Canada. The emergence of VOCs has sparked debate on how to effectively control their impacts on the Canadian population.
Provincial and territorial governments have implemented a wide range of policy measures to protect residents against community transmission of COVID-19, but research examining the specific impact of policy countermeasures on the VOCs in Canada is needed. Our study objective was to identify provinces with disproportionate prevalence of VOCs relative to COVID-19 mitigation efforts in provinces and territories in Canada.
We analyzed publicly available provincial- and territorial-level data on the prevalence of VOCs in relation to mitigating factors, summarized in 3 measures: (1) strength of public health countermeasures (stringency index), (2) the extent to which people moved about outside their homes (mobility index), and (3) the proportion of the provincial or territorial population that was fully vaccinated (vaccine uptake). Using spatial agglomerative hierarchical cluster analysis (unsupervised machine learning), provinces and territories were grouped into clusters by stringency index, mobility index, and full vaccine uptake. The Kruskal-Wallis test was used to compare the prevalence of VOCs (Alpha, or B.1.1.7; Beta, or B.1.351; Gamma, or P.1; and Delta, or B.1.617.2 variants) across the clusters.
We identified 3 clusters of vaccine uptake and countermeasures. Cluster 1 consisted of the 3 Canadian territories and was characterized by a higher degree of vaccine deployment and fewer countermeasures. Cluster 2 (located in Central Canada and the Atlantic region) was typified by lower levels of vaccine deployment and moderate countermeasures. The third cluster, which consisted of provinces in the Pacific region, Central Canada, and the Prairies, exhibited moderate vaccine deployment but stronger countermeasures. The overall and variant-specific prevalences were significantly different across the clusters.
This "up to the point" analysis found that implementation of COVID-19 public health measures, including the mass vaccination of populations, is key to controlling VOC prevalence rates in Canada. As of June 15, 2021, the third wave of COVID-19 in Canada is declining, and those provinces and territories that had implemented more comprehensive public health measures showed lower VOC prevalence. Public health authorities and governments need to continue to communicate the importance of sociobehavioural preventive measures, even as populations in Canada continue to receive their primary and booster doses of vaccines.
有越来越多的证据表明，第三波 COVID-19 发病率正在下降，但令人关注的变异株（VOC）继续对加拿大的公共卫生构成挑战。VOC 的出现引发了关于如何有效控制其对加拿大人口影响的辩论。
省级和地区政府已经实施了广泛的政策措施来保护居民免受 COVID-19 的社区传播，但需要研究考察政策对策对加拿大 VOC 的具体影响。我们的研究目的是确定相对于省级和地区 COVID-19 缓解努力而言，VOC 患病率过高的省份。
我们分析了省级和地区层面上与缓解因素有关的 VOC 患病率的公开数据，总结为 3 个指标：（1）公共卫生对策的强度（严格指数），（2）人们离开家外出活动的程度（流动性指数），以及（3）完全接种疫苗的省或地区人口比例（疫苗接种率）。使用空间聚集层次聚类分析（无监督机器学习），根据严格指数、流动性指数和完全疫苗接种率将省份和地区分为聚类。使用 Kruskal-Wallis 检验比较各聚类之间 VOC（Alpha 或 B.1.1.7；Beta 或 B.1.351；Gamma 或 P.1；和 Delta 或 B.1.617.2 变体）的患病率。
我们确定了 3 个疫苗接种和对策聚类。聚类 1 由 3 个加拿大地区组成，其特点是疫苗部署程度较高，对策较少。聚类 2（位于加拿大中部和大西洋地区）的特点是疫苗部署水平较低，对策适中。第三个聚类由太平洋地区、加拿大中部和草原地区的省份组成，疫苗部署程度适中，但对策较强。总体和变体特异性患病率在聚类之间存在显著差异。
这项“最新”分析发现，实施 COVID-19 公共卫生措施，包括人群的大规模疫苗接种，是控制加拿大 VOC 患病率的关键。截至 2021 年 6 月 15 日，加拿大的第三波 COVID-19 正在下降，实施更全面公共卫生措施的省份和地区的 VOC 患病率较低。加拿大的公共卫生当局和政府需要继续传达社会行为预防措施的重要性，即使加拿大人口继续接种初级和加强疫苗。
