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. 2020 Dec;81(6):931-936.
doi: 10.1016/j.jinf.2020.10.011. Epub 2020 Oct 15.

Estimates of the rate of infection and asymptomatic COVID-19 disease in a population sample from SE England

Philippa M Wells  1 , Katie J Doores  2 , Simon Couvreur  1 , Rocio Martinez Nunez  2 , Jeffrey Seow  2 , Carl Graham  2 , Sam Acors  2 , Neophytos Kouphou  2 , Stuart J D Neil  2 , Richard S Tedder  3 , Pedro M Matos  2 , Kate Poulton  2 , Maria Jose Lista  2 , Ruth E Dickenson  2 , Helin Sertkaya  2 , Thomas J A Maguire  4 , Edward J Scourfield  2 , Ruth C E Bowyer  1 , Deborah Hart  1 , Aoife O'Byrne  4 , Kathryn J A Steel  4 , Oliver Hemmings  5 , Carolina Rosadas  3 , Myra O McClure  3 , Joan Capedevilla-Pujol  6 , Jonathan Wolf  6 , Sebastien Ourselin  7 , Matthew A Brown  8 , Michael H Malim  2 , Tim Spector  1 , Claire J Steves  9
Affiliations

Estimates of the rate of infection and asymptomatic COVID-19 disease in a population sample from SE England

Philippa M Wells et al. J Infect. 2020 Dec.

Abstract

Background: Understanding of the true asymptomatic rate of infection of SARS-CoV-2 is currently limited, as is understanding of the population-based seroprevalence after the first wave of COVID-19 within the UK. The majority of data thus far come from hospitalised patients, with little focus on general population cases, or their symptoms.

Methods: We undertook enzyme linked immunosorbent assay characterisation of IgM and IgG responses against SARS-CoV-2 spike glycoprotein and nucleocapsid protein of 431 unselected general-population participants of the TwinsUK cohort from South-East England, aged 19-86 (median age 48; 85% female). 382 participants completed prospective logging of 14 COVID-19 related symptoms via the COVID Symptom Study App, allowing consideration of serology alongside individual symptoms, and a predictive algorithm for estimated COVID-19 previously modelled on PCR positive individuals from a dataset of over 2 million.

Findings: We demonstrated a seroprevalence of 12% (51 participants of 431). Of 48 seropositive individuals with full symptom data, nine (19%) were fully asymptomatic, and 16 (27%) were asymptomatic for core COVID-19 symptoms: fever, cough or anosmia. Specificity of anosmia for seropositivity was 95%, compared to 88% for fever cough and anosmia combined. 34 individuals in the cohort were predicted to be Covid-19 positive using the App algorithm, and of those, 18 (52%) were seropositive.

Interpretation: Seroprevalence amongst adults from London and South-East England was 12%, and 19% of seropositive individuals with prospective symptom logging were fully asymptomatic throughout the study. Anosmia demonstrated the highest symptom specificity for SARS-CoV-2 antibody response.

Funding: NIHR BRC, CDRF, ZOE global LTD, RST-UKRI/MRC.

Keywords: Anosmia; Antibody; Asymptomatic; COVID-19; Immunity; Population; SARS-CoV-2; Seropoprevalence; UK.

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Figures

Fig. 1
Fig. 1
Antibody levels in relation to symptom pattern. Depicted in A) all participants with antibody profiling and in B) participants are partitioned by predicted COVID status (predCOVID), estimated using the algorithm for prior infection of COVID-19, based on reported symptoms. Antibody levels are measured as fold change in absorbence (OD) above test background.
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References

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