European Surveillance and History of the COVID-19 Pandemic: Updated Epidemiological Assessment.

BACKGROUND:COVID-19 surveillance plays a crucial role in monitoring the pandemic's progression and comprehending its impact on diverse regions. In this study, we build upon our initial research published in 2020 by incorporating an additional two years of data for Europe. We assess whether COVID-19 had shifted from pandemic to endemic in the region when the World Health Organization (WHO) declared the end of the public health emergency for the COVID-19 pandemic on May 5, 2023. OBJECTIVE:First, we measure whether there was an expansion or contraction in the pandemic in Europe at the time of the WHO declaration. Second, we use 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 provide the historical context for the course of the pandemic in Europe in terms of policy and disease burden at the country and region levels. METHODS:In addition to updates of traditional surveillance data and dynamic panel estimates from the original study Post et al. (2021), this study used data on sequenced SARS-CoV-2 variants from the Global Initiative on Sharing All Influenza Data (GISAID) 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 one-sided t-test for whether regional weekly speed was greater than an outbreak threshold of ten. We ran the test iteratively with six months of data across the sample period. RESULTS:Speed for the region had remained below the outbreak threshold for four months by the time of the WHO declaration. Acceleration and jerk were also low and stable. While the 1- and 7-day persistence coefficients remained statistically significant, the coefficients were moderate in magnitude (0.404 and 0.547, respectively). The shift parameters for the two 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 of 2021 onward, Omicron was the predominant variant of concern in sequenced viral samples. The rolling t-test of speed equal to ten became insignificant for the first time in April 2023. CONCLUSIONS:While COVID-19 continues to circulate in Europe, the rate of transmission remained below the threshold of an outbreak for four months ahead of the WHO declaration. The region had previously been in a nearly continuous state of outbreak. The more recent trend suggest 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 pandemic in Europe at the time is unclear. CLINICALTRIAL: