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Background'Classic' symptoms (cough, fever, loss of taste/smell) prompt SARS-CoV-2 PCR-testing in the UK. Studies have assessed the ability of different symptoms to identify infection, but few have compared symptoms over time (reflecting variants) and by vaccination status.MethodsUsing the COVID-19 Infection Survey, sampling households across the UK, we compared symptoms in PCR-positives vs. PCR-negatives, evaluating sensitivity of combinations of 12 symptoms (percentage symptomatic PCR-positives reporting specific symptoms) and tests per case (TPC) (PCR-positives or PCR-negatives reporting specific symptoms/ PCR-positives reporting specific symptoms).ResultsBetween April 2020 and August 2021, 27,869 SARS-CoV-2 PCR-positive episodes occurred in 27,692 participants (median 42 years), of whom 13,427 (48%) self-reported symptoms ("symptomatic PCR-positives"). The comparator comprised 3,806,692 test-negative visits (457,215 participants); 130,612 (3%) self-reported symptoms ("symptomatic PCR-negatives"). Symptom reporting in PCR-positives varied by age, sex, and ethnicity, and over time, reflecting changes in prevalence of viral variants, incidental changes (e.g. seasonal pathogens (with sore throat increasing in PCR-positives and PCR-negatives from April 2021), schools re-opening) and vaccination roll-out. After May-2021 when Delta emerged, headache and fever substantially increased in PCR-positives, but not PCR-negatives. Sensitivity of symptom-based detection increased from 74% using 'classic' symptoms, to 81% adding fatigue/weakness, and 90% including all eight additional symptoms. However, this increased TPC from 4.6 to 5.3 to 8.7.ConclusionsExpanded symptom combinations may provide modest benefits for sensitivity of PCR-based case detection, but this will vary between settings and over time, and increases tests/case. Large-scale changes to targeted PCR-testing approaches require careful evaluation given substantial resource and infrastructure implications.

Original publication

DOI

10.1093/cid/ciab945

Type

Journal article

Journal

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America

Publication Date

08/11/2021

Addresses

Nuffield Department of Medicine, University of Oxford, Oxford, UK.

Keywords

COVID-19 Infection Survey team