Anti-S-RBD IgG day 0; before 2nd dose; 14 days; 90 days; and 180 days after 2nd dose BIOTEC COVID-19 IgG ELISA;Surrogate virus neutralization test (sVNT) to variants of concern day 0; before 2nd dose; 14 days; 90 days; and 180 days after 2nd dose ELISA

Anti-S-RBD IgG day 0; before 2nd dose; 14 days; 90 days; and 180 days after 2nd dose BIOTEC COVID-19 IgG ELISA;Surrogate virus neutralization test (sVNT) to variants of concern day 0; before 2nd dose; 14 days; 90 days; and 180 days after 2nd dose ELISA