Evaluation of the relative virulence of novel SARS-CoV-2 variants: a retrospective cohort study in Ontario, Canada.
Evaluation of the relative virulence of novel SARS-CoV-2 variants: a retrospective cohort study in Ontario, Canada.
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DOI：
10.1503/cmaj.211248
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发表时间：
2021-10-25
期刊：
影响因子：
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通讯作者：
Tuite AR
中科院分区：
文献类型：
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作者：
Fisman DN;Tuite AR
2021年2月至6月，在加拿大安大略省，最初的SARS-CoV-2野生型毒株被新的关注变种(VOC)取代，首先是N501Y突变的毒株(即Alpha/B1.1.17、Beta/B.1.351和Gamma/P.1变种)，然后是Delta/B.1.617变种。这些VOCs的传播性增加已经被记录在案，但关于它们的毒力的知识有限。我们使用安大略省的新冠肺炎病例数据，通过住院、重症监护病房(ICU)入院和死亡的风险来评估这些VOC与非VOC SARS-CoV-2毒株的毒力。我们在安大略省建立了一个追溯队列，这些人的SARS-CoV-2检测呈阳性，并进行了VOCs筛查，检测报告的日期在2021年2月7日至6月27日之间。我们建立了以住院、ICU入院和死亡为结果变量的混合效应Logistic回归模型。我们调整了年龄、性别、时间、疫苗接种状态、合并症和怀孕状态的模型。我们将卫生单位作为随机截获对象。我们的队列包括212,326人。与非VOC SARS-CoV-2毒株相比，N501Y阳性变异株调整后的风险增加住院为52%(95%可信区间42%-63%)，住院89%(95%可信区间67%-117%)，死亡51%(95%可信区间30%-78%)。Delta变异的风险增加更明显，住院的风险为108%(95%CI 78%-140%)，ICU住院的风险为235%(95%CI 160%-331%)，死亡的风险为133%(95%CI 54%-231%)。与没有VOCs出现时相比，SARS-CoV-2 VOCs毒力的增加将导致一场规模更大、更致命的大流行。
Between February and June 2021, the initial wild-type strains of SARS-CoV-2 were supplanted in Ontario, Canada, by new variants of concern (VOCs), first those with the N501Y mutation (i.e., Alpha/B1.1.17, Beta/B.1.351 and Gamma/P.1 variants) and then the Delta/B.1.617 variant. The increased transmissibility of these VOCs has been documented, but knowledge about their virulence is limited. We used Ontario’s COVID-19 case data to evaluate the virulence of these VOCs compared with non-VOC SARS-CoV-2 strains, as measured by risk of hospitalization, intensive care unit (ICU) admission and death. We created a retrospective cohort of people in Ontario who tested positive for SARS-CoV-2 and were screened for VOCs, with dates of test report between Feb. 7 and June 27, 2021. We constructed mixed-effect logistic regression models with hospitalization, ICU admission and death as outcome variables. We adjusted models for age, sex, time, vaccination status, comorbidities and pregnancy status. We included health units as random intercepts. Our cohort included 212 326 people. Compared with non-VOC SARS-CoV-2 strains, the adjusted elevation in risk associated with N501Y-positive variants was 52% (95% confidence interval [CI] 42%–63%) for hospitalization, 89% (95% CI 67%–117%) for ICU admission and 51% (95% CI 30%–78%) for death. Increased risk with the Delta variant was more pronounced at 108% (95% CI 78%–140%) for hospitalization, 235% (95% CI 160%–331%) for ICU admission and 133% (95% CI 54%–231%) for death. The increasing virulence of SARS-CoV-2 VOCs will lead to a considerably larger, and more deadly, pandemic than would have occurred in the absence of the emergence of VOCs.