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SARS-CoV-2 Antibody testing (IgM) also has significant cross-Reactivity with common cold coronaviruses (HKU1, NL63, OC43, 229E). So this also could lead to false positives.
Therefore, there can be potential for false positive test, and false negative test depending on the assay. We also do not have enough data to suggest that having detectable IgG antibodies conveys significant protection.
Take Away: Due to the varying manufacturer quality, potential false results, and unknown protection that IgG antibodies may convey for SARS-CoV-2, antibody testing outside of vaccine response, detecting convalescent plasma, and identification of illness in PCR negative cases has limited value.
Sources:
Zhao J, Yuan Q, Wang H, et al. Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clin Infect Dis. 2020. Click Here for the full article.
Interpreting Diagnostic Tests for SARS-CoV-2. Click Here for the full article.
Antibody Testing - Are We There Yet? - Continued