Sera from asymptomatic to severe
COVID-19 patients were collected. Microneutralization (MN), fluorescence immunoassay (FIA), and
enzyme-linked
immunosorbent assay (ELISA) were performed.
RESULTS: A total of 70 laboratory-confirmed
COVID-19 patients were evaluated, including 15 asymptomatic/
anosmia, 49 mild symptomatic, and 6
pneumonia patients. The production of the
neutralizing antibody was observed in 100% of
pneumonia, 93.9% of mild symptomatic, and 80.0% of asymptomatic/
anosmia groups. All the patients in the
pneumonia group showed high MN titer (≥1:80), while 36.7% of mild symptomatic and 20.0% of asymptomatic/
anosmia groups showed high titer (p < 0.001). Anti-SARS-CoV-2
antibodies could be more sensitively detected by FIA
IgG (98.8%) and ELISA (97.6%) in overall. For the FIA
IgG test, all patients in the
pneumonia group exhibited a high COI value (≥15.0), while 89.8% of mild symptomatic and 73.3% of asymptomatic/
anosmia groups showed a high value (p = 0.049). For the ELISA test, all patients in the
pneumonia group showed a high optical density (OD) ratio (≥3.0), while 65.3% of mild symptomatic and 53.3% of asymptomatic/
anosmia groups showed a high ratio (p = 0.006).
CONCLUSIONS: