Vaccine immunogenicity
Vaccine immunogenicity was evaluated for a subgroup of patients and
controls by measuring serum IgG antibody levels against SARS-CoV-2
trimeric spike S1/S2 glycoproteins, 2–8 weeks after the second and the
third vaccine doses. We used the FDA-authorized LIAISON (DiaSorin,
Sallugia, Italy) quantitative assay. The assay provides an indication
for the presence of neutralizing IgG antibodies against SARS-CoV-2 and
its clinical sensitivity and specificity is >98%. A value
of >15 binding antibody units (BAU) was considered positive
according to the manufacturer’s instructions.