Ascertainment rate of SARS-CoV-2 infections from healthcare and community testing in the UK

Colman, E., Puspitarani, G. A., Enright, J. and Kao, R. R. (2023) Ascertainment rate of SARS-CoV-2 infections from healthcare and community testing in the UK. Journal of Theoretical Biology, 558, 111333. (doi: 10.1016/j.jtbi.2022.111333) (PMID:36347306) (PMCID:PMC9636607)

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The proportion of SARS-CoV-2 infections ascertained through healthcare and community testing is generally unknown and expected to vary depending on natural factors and changes in test-seeking behaviour. Here we use population surveillance data and reported daily case numbers in the United Kingdom to estimate the rate of case ascertainment. We mathematically describe the relationship between the ascertainment rate, the daily number of reported cases, population prevalence, and the sensitivity of PCR and Lateral Flow tests as a function time since exposure. Applying this model to the data, we estimate that 20%-40% of SARS-CoV-2 infections in the UK were ascertained with a positive test with results varying by time and region. Cases of the Alpha variant were ascertained at a higher rate than the wild type variants circulating in the early pandemic, and higher again for the Delta variant and Omicron BA.1 sub-lineage, but lower for the BA.2 sub-lineage. Case ascertainment was higher in adults than in children. We further estimate the daily number of infections and compare this to mortality data to estimate that the infection fatality rate increased by a factor of 3 during the period dominated by the Alpha variant, and declined in line with the distribution of vaccines. This manuscript was submitted as part of a theme issue on "Modelling COVID-19 and Preparedness for Future Pandemics".

Item Type:Articles
Additional Information:This work was supported by the Wellcome Trust [grant number 209818/Z/17/Z].
Glasgow Author(s) Enlighten ID:Enright, Dr Jessica
Authors: Colman, E., Puspitarani, G. A., Enright, J., and Kao, R. R.
College/School:College of Science and Engineering > School of Computing Science
Journal Name:Journal of Theoretical Biology
ISSN (Online):1095-8541
Published Online:05 November 2022
Copyright Holders:Copyright © 2022 The Authors
First Published:First published in Journal of Theoretical Biology 558:111333
Publisher Policy:Reproduced under a Creative Commons License

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