Buehler Center for Health Policy and Economics, Robert J. Havey, MD Institute for Global Health, Northwestern University, Chicago, IL, United States.
Department of Emergency Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
JMIR Public Health Surveill. 2024 Jun 21;10:e53551. doi: 10.2196/53551.
In this study, we built upon our initial research published in 2020 by incorporating an additional 2 years of data for Europe. We assessed whether COVID-19 had shifted from the pandemic to endemic phase in the region when the World Health Organization (WHO) declared the end of the public health emergency of international concern on May 5, 2023.
We first aimed to measure whether there was an expansion or contraction in the pandemic in Europe at the time of the WHO declaration. Second, we used dynamic and genomic surveillance methods to describe the history of the pandemic in the region and situate the window of the WHO declaration within the broader history. Third, we provided the historical context for the course of the pandemic in Europe in terms of policy and disease burden at the country and region levels.
In addition to the updates of traditional surveillance data and dynamic panel estimates from the original study, this study used data on sequenced SARS-CoV-2 variants from the Global Initiative on Sharing All Influenza Data to identify the appearance and duration of variants of concern. We used Nextclade nomenclature to collect clade designations from sequences and Pangolin nomenclature for lineage designations of SARS-CoV-2. Finally, we conducted a 1-tailed t test for whether regional weekly speed was greater than an outbreak threshold of 10. We ran the test iteratively with 6 months of data across the sample period.
Speed for the region had remained below the outbreak threshold for 4 months by the time of the WHO declaration. Acceleration and jerk were also low and stable. While the 1-day and 7-day persistence coefficients remained statistically significant, the coefficients were moderate in magnitude (0.404 and 0.547, respectively; P<.001 for both). The shift parameters for the 2 weeks around the WHO declaration were small and insignificant, suggesting little change in the clustering effect of cases on future cases at the time. From December 2021 onward, Omicron was the predominant variant of concern in sequenced viral samples. The rolling t test of speed equal to 10 became insignificant for the first time in April 2023.
While COVID-19 continues to circulate in Europe, the rate of transmission remained below the threshold of an outbreak for 4 months ahead of the WHO declaration. The region had previously been in a nearly continuous state of outbreak. The more recent trend suggested that COVID-19 was endemic in the region and no longer reached the threshold of the pandemic definition. However, several countries remained in a state of outbreak, and the conclusion that COVID-19 was no longer a pandemic in Europe at the time is unclear.
本研究在我们 2020 年发表的初步研究基础上，纳入了欧洲另外 2 年的数据。我们评估了在世界卫生组织（WHO）于 2023 年 5 月 5 日宣布结束国际关注的突发公共卫生事件时，该地区的 COVID-19 是否已从大流行阶段进入流行阶段。
首先，我们旨在衡量在 WHO 宣布之时，欧洲大流行是否在扩张或收缩。其次，我们使用动态和基因组监测方法来描述该地区大流行的历史，并将 WHO 宣布的窗口期置于更广泛的历史背景中。第三，我们从国家和地区层面的政策和疾病负担方面为欧洲大流行的进程提供历史背景。
除了对原始研究中的传统监测数据和动态面板估计进行更新外，本研究还使用了来自全球共享所有流感数据倡议的 SARS-CoV-2 测序变体数据，以确定关注变体的出现和持续时间。我们使用 Nextclade 命名法从序列中收集分支名称，并使用 Pangolin 命名法对 SARS-CoV-2 的谱系名称进行分类。最后，我们对区域每周速度是否大于 10 的暴发阈值进行了单侧 t 检验。我们使用样本期内 6 个月的数据迭代进行了测试。
到 WHO 宣布之时，该地区的速度已经连续 4 个月低于暴发阈值。加速度和急动度也较低且稳定。虽然 1 天和 7 天的持续系数仍具有统计学意义，但系数的幅度适中（分别为 0.404 和 0.547；两者均 P<.001）。在 WHO 宣布前后的两周内，转移参数很小且无统计学意义，这表明未来病例的病例聚类效应几乎没有变化。自 2021 年 12 月以来，Omicron 一直是测序病毒样本中主要的关注变体。2023 年 4 月，速度的滚动 t 检验首次变得不显著。
尽管 COVID-19 在欧洲继续传播，但在 WHO 宣布前的 4 个月内，传播率仍低于暴发阈值。该地区此前一直处于几乎连续的暴发状态。最近的趋势表明，COVID-19 在该地区已成为流行，不再符合大流行定义的阈值。然而，一些国家仍处于暴发状态，因此当时 COVID-19 在欧洲不再是大流行的结论尚不清楚。
