COVID-19 Publications

Recruitment took place between April 16, and July 3, 2020, at five UK sites (Belfast, Cardiff, Glasgow, London, and Manchester) and included healthy children aged 2–15 years. Follow-up visits at all five UK sites took place between June 26, and Aug 15, 2020.

Of the 992 participants in the first round, 849 (86%) returned. Seroprevalence was measured with the Elecsys Anti-SARS-CoV-2 Total Antibody assay (Roche, Basel, Switzerland) and the LIAISON SARS-CoV-2 S1/S2 IgG assay (DiaSorin, Saluggia, Italy). The median time between initial and follow-up visits was 62 days (IQR 52–70; range 43–81). 65 (7·66%, 95% CI 6·05–9·64) of 849 tests were reactive based on the manufacturers’ suggested cutoffs. This proportion was not substantially different to the seroprevalence (6·9% 95% CI 5·4 to 8·6; 68 of 992) reported during recruitment. The median age of participants with reactive antibody tests during the second round was 10 years (IQR 7–14; range 3–16). As with the baseline results, there was variation in seroprevalence between sites.