Immunisation and Vaccine Preventable Diseases Division, UK Health Security Agency, London, UK.
Epidemiol Infect. 2022 May 24;150:e109. doi: 10.1017/S0950268822000966.
The duration of immunity after first severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the extent to which prior immunity prevents reinfection is uncertain and remains an important question within the context of new variants. This is a retrospective population-based matched observational study where we identified the first polymerase chain reaction (PCR) positive of primary SARS-CoV-2 infection case tests between 1 March 2020 and 30 September 2020. Each case was matched by age, sex, upper tier local authority of residence and testing route to one individual testing negative in the same week (controls) by PCR. After a 90-day pre-follow-up period for cases and controls, any subsequent positive tests up to 31 December 2020 and deaths within 28 days of testing positive were identified, this encompassed an essentially vaccine-free period. We used a conditional logistic regression to analyse the results. There were 517 870 individuals in the matched cohort with 2815 reinfection cases and 12 098 first infections. The protective effect of a prior SARS-CoV-2 PCR-positive episode was 78% (odds ratio (OR) 0.22, 0.21-0.23). Protection rose to 82% (OR 0.18, 0.17-0.19) after a sensitivity analysis excluded 933 individuals with a first test between March and May and a subsequent positive test between June and September 2020. Amongst individuals testing positive by PCR during follow-up, reinfection cases had 77% lower odds of symptoms at the second episode (adjusted OR 0.23, 0.20-0.26) and 45% lower odds of dying in the 28 days after reinfection (adjusted OR 0.55, 0.42-0.71). Prior SARS-CoV-2 infection offered protection against reinfection in this population. There was some evidence that reinfections increased with the alpha variant compared to the wild-type SARS-CoV-2 variant highlighting the importance of continued monitoring as new variants emerge.
首次感染严重急性呼吸综合征冠状病毒 2 （SARS-CoV-2）后的免疫持续时间，以及先前的免疫在多大程度上能预防再次感染，这些在新变体的背景下仍是一个重要问题。这是一项回顾性基于人群的匹配观察性研究，我们在 2020 年 3 月 1 日至 9 月 30 日期间，确定了首例聚合酶链反应（PCR）阳性的原发性 SARS-CoV-2 感染病例检测。每个病例均按年龄、性别、上一级地方政府行政区和检测途径与同一周内 PCR 检测阴性的一个个体（对照）相匹配。对病例和对照进行 90 天的随访前阶段后，确定了任何随后在 2020 年 12 月 31 日前的阳性检测结果和检测阳性后 28 天内的死亡情况，这涵盖了一个基本上没有接种疫苗的时期。我们使用条件逻辑回归分析结果。在匹配队列中有 517870 人，有 2815 例再感染病例和 12098 例首次感染。先前的 SARS-CoV-2 PCR 阳性事件的保护作用为 78%（比值比（OR）0.22，0.21-0.23）。在一项敏感性分析中排除了 933 名 2020 年 3 月至 5 月首次检测后、6 月至 9 月间再次检测阳性的个体后，保护作用上升至 82%（OR 0.18，0.17-0.19）。在随访期间通过 PCR 检测呈阳性的个体中，再感染病例的第二次感染时出现症状的几率降低了 77%（调整后的 OR 0.23，0.20-0.26），并且在再感染后 28 天内死亡的几率降低了 45%（调整后的 OR 0.55，0.42-0.71）。先前的 SARS-CoV-2 感染为该人群提供了对再感染的保护。有证据表明，与野生型 SARS-CoV-2 变体相比，α变体的再感染有所增加，这凸显了随着新变体的出现，持续监测的重要性。
