Lagerqvist N, Maleki KT, Verner-Carlsson J, Olausson M, Dillner J, Wigren Byström J, Monsen T, Forsell M, Eriksson J, Bogdanovic G, Muschiol S, Ljunggren J, Repo J, Kjerstadius T, Muradrasoli S, Brytting M, Szekely Björndal Å, Åkerlund T, Nilsson C, Klingström J
Sci Rep 11 (1) 7614 [2021-04-07; online 2021-04-07]
We evaluated the performance of 11 SARS-CoV-2 antibody tests using a reference set of heat-inactivated samples from 278 unexposed persons and 258 COVID-19 patients, some of whom contributed serial samples. The reference set included samples with a variation in SARS-CoV-2 IgG antibody titers, as determined by an in-house immunofluorescence assay (IFA). The five evaluated rapid diagnostic tests had a specificity of 99.0% and a sensitivity that ranged from 56.3 to 81.6% and decreased with low IFA IgG titers. The specificity was > 99% for five out of six platform-based tests, and when assessed using samples collected ≥ 22 days after symptom onset, two assays had a sensitivity of > 96%. These two assays also detected samples with low IFA titers more frequently than the other assays. In conclusion, the evaluated antibody tests showed a heterogeneity in their performances and only a few tests performed well with samples having low IFA IgG titers, an important aspect for diagnostics and epidemiological investigations.