Given the high risks for this population, the levels of anti-spike protein antibodies against SARS-CoV-2 were measured in patients and healthcare workers after they received anti-COVID vaccination at the two facilities to prevent a COVID-19 outbreak. Anti-spike protein antibodies were measured using the Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics International Ltd., Switzerland) at three time points, 3 weeks after the first injection, and at 2 and 3 weeks after the second injection, respectively. The “lower detection limit” and “cut-off level for a seronegative result” were 0.4 U/mL and 0.8 U/mL, respectively. An effective protective IgG level was determined to be ≥ 29 U/mL [14 ] based on the reported virus-neutralization ability [15 (link)]. Furthermore, we tested the presence of nucleocapsid (N) antibodies using the Elecsys® assay to exclude subjects with a COVID-19 history [cut-off index < 1.0 interpreted as non-reactive (negative)]. Patient background data were obtained from their medical records, and routine blood test results were obtained just before the first dose of BNT162b2 was administered as part of routine clinical practice. Blood test results and body mass index of healthcare workers were obtained during the routine health check.
Free full text: Click here
