Table 4. Viral-neutralizing antibody titers assessed by live virus neutralization assay (VNT50, PRNT50, and FRNT50) against SARS-CoV-2 wild-type (WT) and Omicron BA.1/BA.2 subvariants upon homologous boosting.
| Vaccinesa (Homo-booster)a |
Participants (No./Reference) |
NeuAb assay (Method/Unit) |
WT (GMT)b |
Omicrons BA.1/BA.2 (GMT)b |
WT/Omicrons BA.1/BA.2 (GMFR) |
|---|---|---|---|---|---|
| UB-612 | (n = 15)/(ref. 52) | MNA/VNT50 | 6,159 | 670/485 | 9.2/12.7 |
| mRNA-1273 | (n = 20)/(ref. 7) | FRNT/ID50 | 1659 | 81.0/ND | 20.5/ND |
| BNT162b2 | (n = 20)/(ref. 7) | FRNT/ID50 | 640 | 46.2/ND | 13.3/ND |
| BNT162b2 | (n = 30)/(ref. 35) | PRNT/VNT50 | 673 | 106/ND | 6.3/ND |
| AZD1222 | (n = 41)/(Ref. 53) | FRNT/FRNT50 | 723 | 57.0/ND | 12.7/ND |
Abbreviation: MNA = Microneutralization assay; PRNT = plaque reduction neutralization test; FRNT = focus reduction neutralization test; GMT = geometric mean titer; GMFR = geometric mean fold reduction relative to WT; WT = wild type strain of SARS-CoV-2; Omicrons = Omicron subvariants BA.1/BA.2; ND = not determined. pVNT50 & ID50 = 50% neutralization GMT by live virus assay; VNT50, ID50 & FRNT50 = 50% neutralization GMT by live virus assay.
a Vaccines reported of homologous booster (third dose) vaccination.
b GMTs against WT measured at 14 or 28 days post-booster third dose.