Evaluation of the performance of SARS-CoV-2 serological tools and their positioning in COVID-19 diagnostic strategies

Rapid and accurate diagnosis is crucial for successful outbreak containment. During the current COVID-19 public health emergency, the gold standard for SARS-CoV-2 infection diagnosis is the detection of viral RNA. Additional diagnostic methods enabling the detection of current or past SARS-CoV-2 infection would be highly beneficial. We assessed two immunochromatographic lateral flow assays (LFA-1, LFA-2) and two ELISA kits (IgA /IgG ELISA-1, IgM /IgG ELISA-2) using 325 samples: serum samples from PCR-confirmed COVID-19 hospitalized patients (n = 55) and healthcare workers (n = 143) and 127 samples from negative controls. Diagnostic performances were assessed according to days after symptom onset (dso) and the antigenic format used by manufacturers. Clinical sensitivities varied greatly among the assays, showing poor mutual agreement. After 15 dso, ELISA-1 (Euroimmun) and LFA-1 (Biosynex) combining IgM and IgG detection showed the best performances. A thorough selection of serological assays for the detection of ongoing or past infections is advisable.
Highlights • We assessed two immunochromatographic lateral flow assays (LFA-1, LFA-2) and two ELISA kits (IgA /IgG ELISA-1, IgM /IgG ELISA-2) using 325 well-characterized samples • The clinical sensitivity varied greatly according to days after symptom onset, the antigenic format and the disease severity. • The assays showed poor mutual agreement. • A thorough selection of serological assays for the detection of ongoing or past infections is advisable.