COVID-19(10) SARS-CoV-2(7) reported(7) Mild(7) serum samples(5) sensitivities(5) Laboratory(5) tested(5) Cohort(5) ranged(5) Evaluation(5) Roche(5) best(5) post-symptom onset(5) antibodies(5) serum sample(5) diagnostic(5) sensitivity(5) SARS-CoV-2 antibody(5) critical appraisal(5) immunoassay.(5) confirmation(5) electrochemiluminescence immunoassay(5) IgG(5) immunoassay(5) S1 and S2(5) Characteristics(5) asymptomatic subject(5) ELISA assay(5) reference material(5)