This study compared 4 commercial ELISAs and 2 rapid tests for detecting antibodies in individuals with PCR-confirmed SARS-CoV-2 infection and found that while test sensitivities were low within the first 5 days, by >10 days, all evaluated tests provided positive results >10 days post disease onset.
- Compared tests:
- Four ELISAs – Euroimmun SARS-CoV-2 IgA and IgG, Wantai SARS-CoV-2 IgM and total antibodies
- Two rapid tests (Wantai SARS-CoV-2 Ab Rapid Test and 2019-nCoV IgG/IgM Rapid Test)
- Serum or plasma from 77 symptomatic patients with acute SARS-CoV-2 infection, who were diagnosed by positive PCR were used
- Serum samples from 100 indivdiuals without SARS-CoV-2 served as controls
- Sensitivities were low (<40%) within the first 5 days post disease onset, IgM-, IgA- and total antibody-ELISAs increased in sensitivity to >80% between the 6th and 10th day post symptom onset. The evaluated tests (including IgG and rapid tests) provided positive results in ALL patients >10th day post onset of disease.
- Specificities were 83% and 98% for the Euroimmun IgA and IgG and 97% for the Wantai IgM and the Ab ELISAs, respectively
- The Wantai Rapid Test displayed a specificity of 98%, and the 2019-2019-nCoV IgG/IgM Rapid Test 100% for IgM and IgG respectively