Antibody testing for COVID-19: A report from the National COVID Scientific Advisory Panel
Authors: Adams Emily R. , Ainsworth Mark , Anand Rekha , Andersson Monique I. , Auckland Kathryn , Baillie J. Kenneth , Barnes Eleanor , Beer Sally , Bell John I. , Berry Tamsin , Bibi Sagida , Carroll Miles , Chinnakannan Senthil K. , Clutterbuck Elizabeth , Cornall Richard J. , Crook Derrick W. , de Silva Thushan , Dejnirattisai Wanwisa , Dingle Kate E. , Dold Christina , Espinosa Alexis , Eyre David W. , Farmer Helen , Fernandez Mendoza Maria , Georgiou Dominique , Hoosdally Sarah J. , Hunter Alastair , Jefferey Katie , Kelly Dominic F. , Klenerman Paul , Knight Julian , Knowles Clarice , Kwok Andrew J. , Leuschner Ullrich , Levin Robert , Liu Chang , López-Camacho César , Martinez Jose , Matthews Philippa C. , McGivern Hannah , Mentzer Alexander J. , Milton Jonathan , Mongkolsapaya Juthathip , Moore Shona C. , Oliveira Marta S. , Pereira Fiona , Perez Elena , Peto Timothy , Ploeg Rutger J. , Pollard Andrew , Prince Tessa , Roberts David J. , Rudkin Justine K. , Sanchez Veronica , Screaton Gavin  R. , Semple Malcolm G. , Slon-Campos Jose , Skelly Donal T. , Smith Elliot Nathan , Sobrinodiaz Alberto , Staves Julie , Stuart David I. , Supasa Piyada , Surik Tomas , Thraves Hannah , Tsang Pat , Turtle Lance , Walker A. Sarah , Wang Beibei , Washington Charlotte , Watkins Nicholas , Whitehouse James ,   National COVID Testing Scientific Advisory Panel
Published: June 2020

Background: The COVID-19 pandemic caused >1 million infections during January-March 2020. There is an urgent need for reliable antibody detection approaches to support diagnosis, vaccine development, safe release of individuals from quarantine, and population lock-down exit strategies. We set out to evaluate the performance of ELISA and lateral flow immunoassay (LFIA) devices.

Methods: We tested plasma for COVID (severe acute respiratory syndrome coronavirus 2; SARS-CoV-2) IgM and IgG antibodies by ELISA and using nine different LFIA devices. We used a panel of plasma samples from individuals who have had confirmed COVID infection based on a PCR result (n=40), and pre-pandemic negative control samples banked in the UK prior to December-2019 (n=142).

Results: ELISA detected IgM or IgG in 34/40 individuals with a confirmed history of COVID infection (sensitivity 85%, 95%CI 70-94%), vs. 0/50 pre-pandemic controls (specificity 100% [95%CI 93-100%]). IgG levels were detected in 31/31 COVID-positive individuals tested ≥10 days after symptom onset (sensitivity 100%, 95%CI 89-100%). IgG titres rose during the 3 weeks post symptom onset and began to fall by 8 weeks, but remained above the detection threshold. Point estimates for the sensitivity of LFIA devices ranged from 55-70% versus RT-PCR and 65-85% versus ELISA, with specificity 95-100% and 93-100% respectively. Within the limits of the study size, the performance of most LFIA devices was similar.

Conclusions: Currently available commercial LFIA devices do not perform sufficiently well for individual patient applications. However, ELISA can be calibrated to be specific for detecting and quantifying SARS-CoV-2 IgM and IgG and is highly sensitive for IgG from 10 days following first symptoms.