Immunogenicity
Immunogenicity outcomes were evaluated at baseline (pre-dose 1),
post-dose 1 (pre-dose 2, 21-28 days after dose 1), post-dose 2 (28 days
after dose 2), pre-dose 3 (at least 28 days after dose 2), and post-dose
3 (28 days after dose 3). Primary humoral immunogenicity outcomes
include wild-type (WT) Spike receptor-binding domain (S-RBD) IgG ELISA
and WT surrogate virus neutralization test (sVNT), and secondary
outcomes include BA.1 sVNT. WT S-RBD IgG enzyme-linked immunosorbent
assay (ELISA) were carried out as previously described and
validated.15,25 sVNT was conducted according to the
manufacturer’s instructions (GenScript Inc, Piscataway, USA) and as
described in our previous publications.25IFN-γ+ or IL-2+CD4+ or CD8+ T cell responses were
examined by intracellular cytokine staining after stimulation with
SARS-CoV-2 S peptide pool (and N and M peptide pools for CoronaVac
recipients) (Miltenyi Biotec, Bergisch Gladbach, Germany) as a primary
cellular outcome as described previously.15,24Frequencies of T cell responses against S, N and M peptide pools are
added together for CoronaVac recipients. Negative values, i.e., below
the limit of detection (LOD), limit of quantification (LOQ) or cut-off,
are imputed as half the limit/cut-off. All available results from IEI
patients who received at least one dose, prior to the analysis, were
presented. Additional details are available in the Supplemental
Methods.