Office for National Statistics, Newport, UK.
Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, UK.
BMJ. 2022 Aug 2;378:e070695. doi: 10.1136/bmj-2022-070695.
To assess the risk of covid-19 death after infection with omicron BA.1 compared with delta (B.1.617.2).
Retrospective cohort study.
England, United Kingdom, from 1 December 2021 to 30 December 2021.
1 035 149 people aged 18-100 years who tested positive for SARS-CoV-2 under the national surveillance programme and had an infection identified as omicron BA.1 or delta compatible.
The main outcome measure was covid-19 death as identified from death certification records. The exposure of interest was the SARS-CoV-2 variant identified from NHS Test and Trace PCR positive tests taken in the community (pillar 2) and analysed by Lighthouse laboratories. Cause specific Cox proportional hazard regression models (censoring non-covid-19 deaths) were adjusted for sex, age, vaccination status, previous infection, calendar time, ethnicity, index of multiple deprivation rank, household deprivation, university degree, keyworker status, country of birth, main language, region, disability, and comorbidities. Interactions between variant and sex, age, vaccination status, and comorbidities were also investigated.
The risk of covid-19 death was 66% lower (95% confidence interval 54% to 75%) for omicron BA.1 compared with delta after adjusting for a wide range of potential confounders. The reduction in the risk of covid-19 death for omicron compared with delta was more pronounced in people aged 18-59 years (number of deaths: delta=46, omicron=11; hazard ratio 0.14, 95% confidence interval 0.07 to 0.27) than in those aged ≥70 years (number of deaths: delta=113, omicron=135; hazard ratio 0.44, 95% confidence interval 0.32 to 0.61, P<0.0001). No evidence of a difference in risk was found between variant and number of comorbidities.
The results support earlier studies showing a reduction in severity of infection with omicron BA.1 compared with delta in terms of hospital admission. This study extends the research to also show a reduction in the risk of covid-19 death for the omicron variant compared with the delta variant.
评估感染奥密克戎 BA.1 后的新冠死亡风险与感染德尔塔（B.1.617.2）的风险相比。
回顾性队列研究。
英国英格兰，2021 年 12 月 1 日至 12 月 30 日。
1035149 名年龄在 18-100 岁之间的人，他们在国家监测计划中检测出 SARS-CoV-2 呈阳性，并通过 NHS Test and Trace PCR 检测出奥密克戎 BA.1 或德尔塔兼容的感染。
主要结局指标是从死亡证明记录中确定的新冠死亡。感兴趣的暴露因素是 NHS Test and Trace PCR 阳性社区检测（支柱 2）中识别出的 SARS-CoV-2 变异，并由 Lighthouse 实验室进行分析。原因特异性 Cox 比例风险回归模型（对非新冠死亡进行删失）调整了性别、年龄、疫苗接种状况、既往感染、日历时间、种族、多因素剥夺等级、家庭剥夺、大学学位、关键工作者状况、出生地、主要语言、地区、残疾和合并症。还研究了变异与性别、年龄、疫苗接种状况和合并症之间的相互作用。
在调整了广泛的潜在混杂因素后，与德尔塔相比，奥密克戎 BA.1 导致新冠死亡的风险降低了 66%（95%置信区间为 54%至 75%）。与德尔塔相比，奥密克戎降低新冠死亡风险的幅度在 18-59 岁人群中更为显著（死亡人数：德尔塔=46，奥密克戎=11；风险比 0.14，95%置信区间 0.07 至 0.27），而在≥70 岁人群中则不显著（死亡人数：德尔塔=113，奥密克戎=135；风险比 0.44，95%置信区间 0.32 至 0.61，P<0.0001）。未发现变异与合并症数量之间存在风险差异的证据。
结果支持了早期研究，表明与德尔塔相比，奥密克戎 BA.1 感染的严重程度在住院方面有所降低。本研究扩展了研究范围，还表明与德尔塔相比，奥密克戎变异导致新冠死亡的风险降低。
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