Background

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has caused a pandemic with tens of millions of cases and hundreds of thousands of deaths. The infection causes COVID-19, a disease of the respiratory system of divergent severity. Here, the humoral immune response of a cohort of 143 COVID-19 patients from the University Hospital Frankfurt/Main, Germany was characterized.

Methods

SARS-CoV-2-specific antibodies were detected by enzyme-linked immunosorbent assay (ELISA). SARS-CoV-2 and hCoV NL63 neutralization activity was analyzed with pseudotyped lentiviral vectors.

Results

COVID-19 severity increased with age and male patients encountered more serious symptoms than females. Disease severity correlated with the amount of SARS-CoV-2 specific IgG and IgA and the neutralization activity of the antibodies. The amount of SARS-CoV-2 specific IgG antibodies decreased with time after PCR conformation of the infection and antibodies directed against the nucleoprotein waned faster than spike directed antibodies. In contrast, for the common flu coronavirus NL63, COVID19 disease severity seemed to correlate with low NL63-neutralizing activities, suggesting the possibility of cross-reactive protection.

Conclusion

The results describe the humoral immune responses against SARS-CoV-2 and might aid the identification of correlates of protection needed for vaccine development.