Public Health England Colindale, London, UK; The National Institute for Health Research Health Protection Research (NIHR) Unit in Healthcare Associated Infections and Antimicrobial Resistance at the University of Oxford, Oxford, UK.
Public Health England Colindale, London, UK.
Lancet. 2021 May 8;397(10286):1725-1735. doi: 10.1016/S0140-6736(21)00790-X. Epub 2021 Apr 23.
BNT162b2 mRNA and ChAdOx1 nCOV-19 adenoviral vector vaccines have been rapidly rolled out in the UK from December, 2020. We aimed to determine the factors associated with vaccine coverage for both vaccines and documented the vaccine effectiveness of the BNT162b2 mRNA vaccine in a cohort of health-care workers undergoing regular asymptomatic testing.
The SIREN study is a prospective cohort study among staff (aged ≥18 years) working in publicly-funded hospitals in the UK. Participants were assigned into either the positive cohort (antibody positive or history of infection [indicated by previous positivity of antibody or PCR tests]) or the negative cohort (antibody negative with no previous positive test) at the beginning of the follow-up period. Baseline risk factors were collected at enrolment, symptom status was collected every 2 weeks, and vaccination status was collected through linkage to the National Immunisations Management System and questionnaires. Participants had fortnightly asymptomatic SARS-CoV-2 PCR testing and monthly antibody testing, and all tests (including symptomatic testing) outside SIREN were captured. Data cutoff for this analysis was Feb 5, 2021. The follow-up period was Dec 7, 2020, to Feb 5, 2021. The primary outcomes were vaccinated participants (binary ever vacinated variable; indicated by at least one vaccine dose recorded by at least one of the two vaccination data sources) for the vaccine coverage analysis and SARS-CoV-2 infection confirmed by a PCR test for the vaccine effectiveness analysis. We did a mixed-effect logistic regression analysis to identify factors associated with vaccine coverage. We used a piecewise exponential hazard mixed-effects model (shared frailty-type model) using a Poisson distribution to calculate hazard ratios to compare time-to-infection in unvaccinated and vaccinated participants and estimate the impact of the BNT162b2 vaccine on all PCR-positive infections (asymptomatic and symptomatic). This study is registered with ISRCTN, number ISRCTN11041050, and is ongoing.
23 324 participants from 104 sites (all in England) met the inclusion criteria for this analysis and were enrolled. Included participants had a median age of 46·1 years (IQR 36·0-54·1) and 19 692 (84%) were female; 8203 (35%) were assigned to the positive cohort at the start of the analysis period, and 15 121 (65%) assigned to the negative cohort. Total follow-up time was 2 calendar months and 1 106 905 person-days (396 318 vaccinated and 710 587 unvaccinated). Vaccine coverage was 89% on Feb 5, 2021, 94% of whom had BNT162b2 vaccine. Significantly lower coverage was associated with previous infection, gender, age, ethnicity, job role, and Index of Multiple Deprivation score. During follow-up, there were 977 new infections in the unvaccinated cohort, an incidence density of 14 infections per 10 000 person-days; the vaccinated cohort had 71 new infections 21 days or more after their first dose (incidence density of eight infections per 10 000 person-days) and nine infections 7 days after the second dose (incidence density four infections per 10 000 person-days). In the unvaccinated cohort, 543 (56%) participants had typical COVID-19 symptoms and 140 (14%) were asymptomatic on or 14 days before their PCR positive test date, compared with 29 (36%) with typical COVID-19 symptoms and 15 (19%) asymptomatic in the vaccinated cohort. A single dose of BNT162b2 vaccine showed vaccine effectiveness of 70% (95% CI 55-85) 21 days after first dose and 85% (74-96) 7 days after two doses in the study population.
Our findings show that the BNT162b2 vaccine can prevent both symptomatic and asymptomatic infection in working-age adults. This cohort was vaccinated when the dominant variant in circulation was B1.1.7 and shows effectiveness against this variant.
Public Health England, UK Department of Health and Social Care, and the National Institute for Health Research.
自 2020 年 12 月以来，英国迅速推出了 BNT162b2 mRNA 和 ChAdOx1 nCOV-19 腺病毒载体疫苗。我们旨在确定与这两种疫苗接种相关的因素，并在接受定期无症状检测的医护人员队列中记录 BNT162b2 mRNA 疫苗的疫苗有效性。
SIREN 研究是一项在英国公立医院工作的员工（年龄≥18 岁）的前瞻性队列研究。参与者在随访期开始时被分配到阳性队列（抗体阳性或感染史[以前的抗体或 PCR 检测阳性表明]）或阴性队列（抗体阴性且以前无阳性检测）。在入组时收集基线风险因素，每两周收集一次症状状态，通过与国家免疫管理系统和问卷链接收集疫苗接种情况。参与者每两周进行一次无症状 SARS-CoV-2 PCR 检测和每月进行一次抗体检测，SIREN 之外的所有检测（包括症状检测）都被捕获。本分析的数据截止日期为 2021 年 2 月 5 日。随访期为 2020 年 12 月 7 日至 2021 年 2 月 5 日。主要结局是接受过疫苗接种的参与者（至少有一种疫苗剂量被至少两种疫苗接种数据源之一记录的二进制变量；ever vacinated），用于疫苗接种覆盖分析，以及通过 PCR 检测确认的 SARS-CoV-2 感染，用于疫苗有效性分析。我们进行了混合效应逻辑回归分析，以确定与疫苗接种覆盖相关的因素。我们使用分段指数风险混合效应模型（共享比例模型）和泊松分布来计算风险比，以比较未接种疫苗和接种疫苗的参与者的感染时间，并估计 BNT162b2 疫苗对所有 PCR 阳性感染（无症状和有症状）的影响。本研究在 ISRCTN 注册，编号 ISRCTN11041050，正在进行中。
来自 104 个地点（均在英格兰）的 23324 名参与者符合本分析的纳入标准并被纳入。纳入的参与者中位年龄为 46.1 岁（IQR 36.0-54.1），19692 名（84%）为女性；8203 名（35%）在分析期开始时被分配到阳性队列，15121 名（65%）被分配到阴性队列。总随访时间为 2 个日历月和 1106905 人天（396318 人接种疫苗，710587 人未接种疫苗）。2021 年 2 月 5 日疫苗接种覆盖率为 89%，其中 94%接种了 BNT162b2 疫苗。以前的感染、性别、年龄、种族、工作角色和多个贫困指数得分与较低的疫苗接种率显著相关。在随访期间，未接种疫苗的队列中有 977 例新感染，发病率为每 10000 人天 14 例；接种疫苗的队列在第一剂后 21 天或以上有 71 例新感染（每 10000 人天 8 例感染），第二剂后 7 天有 9 例感染（每 10000 人天 4 例感染）。在未接种疫苗的队列中，543 名（56%）参与者有典型的 COVID-19 症状，140 名（14%）在 PCR 阳性检测日期前 14 天或当天无症状，而接种疫苗的队列中，29 名（36%）有典型的 COVID-19 症状，15 名（19%）无症状。接种一剂 BNT162b2 疫苗对 21 天后的疫苗有效性为 70%（95%CI 55-85），7 天后的疫苗有效性为 85%（74-96）。
我们的研究结果表明，BNT162b2 疫苗可以预防成年工作人群的有症状和无症状感染。本队列在循环中的主要变体为 B1.1.7 时进行了疫苗接种，并显示出对该变体的有效性。
英国公共卫生部、英国卫生部和社会保障部以及国家卫生研究院。
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