Quantitative pan-immunoglobulin titers against the receptor binding domain of the SARS-CoV-2 spike protein following infection with SARS-CoV-2

ABSTRACT

Aim: We aimed to determine the distribution of WHO-standardized quantitative measurements of pan-immunoglobulin titers against the receptor binding domain of the SARS-CoV-2 spike protein following SARSCoV- 2 infection. Design & Methods: In a retrospective analysis we analyzed anonymized routine data of patient samples with SARS-CoV-2 infection, as evidenced with a pan-immunoglobulin assay directed against nucleocapsid-antigen measured with an electrochemiluminescence immunoassay (ECLIA;Roche Diagnostics, Switzerland). Pan-immunoglobulin titers of antibodies directed against the receptor binding domain of the SARS-CoV-2 spike protein were measured with the same technology. Results are given as binding antibody units (BAU) per mL. Cut-off for positivity is >0.8 BAU/mL Results: A total of 1436 samples originating from patients (635 males;801 females) aged 52 (median, interquartile range, IQR, [38,64]) years were included. There was no correlation between age and antibody titers Females (111, IQR [27,>257] BAU/mL) had significantly lower median antibody titers than males (147, IQR [36,>257] BAU/mL;p = 0.03) The antibody levels at the 2.5, 5, 10, 25, 68th percentiles were 1,3,6,27 and >257 BAU/ml, in females. The antibody levels at the 2.5, 5, 10, 25 62nd percentiles were 0.4, 2, 9, 36, and >257 BAU/ml in males Conclusions: Among patients with evidence of past SARS-CoV-2 infection one third exhibits antibody titers above the upper quantification limit (i.e. 257 BAU/mL). Fifteen percent of female and 12% of male patients have antibody titers of 10 BAU/mL or lower.