Table 2.
Anti-RBD IgG levels and neutralizing antibodies in vaccinated and vaccinated breakthrough infections.
| Post third dose | Post fourth Dose | Comparison | ||||
|---|---|---|---|---|---|---|
| n | n | p-value | ||||
| Anti-RBD IgG titers BAU/ml | ||||||
| Non-infected | ||||||
| Mean (95%CI) | 40 | 1987 (1462; 2512) | 40 | 2025 (1522; 2528) | 0.859a | |
| Median [Q1-Q3] | 1164 [767; 3237] | 1730 [651; 2850] | 0.547* | |||
| Time adjusted mean (95%CI) | 40 | 1590 (1170; 2009) | 40 | 2025 (1522; 2528) | 0.030a | |
| Breakthrough | ||||||
| Mean (95%CI) | 6 | 1064 (418; 1711) | 6 | 4,603 (2818; 6389) | 0.007a | |
| Median [Q1–Q3] | 985 [698; 1572] | 5,680 [2979; 5680] | 0.028* | |||
| Neutralizing antibodies titers NT50 | ||||||
| Non-infected | ||||||
| WT | Mean (95%CI) | 40 | 1046 (711; 1382) | 40 | 1573 (1044; 2102) | 0.002a |
| Median [Q1-Q3] | 40 | 669 [333; 1629] | 40 | 1166 [496;1684] | 0.001* | |
| BA.1 | Mean (95%CI) | 40 | 170 (85; 255) | 40 | 375 (176; 575) | 0.018a |
| Median [Q1-Q3] | 40 | 50 [2; 234] | 40 | 206 [2; 360] | 0.001* | |
| Breakthrough | ||||||
| WT | Mean (95%CI) | 6 | 696 (398; 993) | 6 | 7872 (2435; 13,310) | 0.022a |
| Median [Q1–Q3] | 645 [476; 959] | 8349 [2036; 13,132] | 0.028* | |||
| BA.1 | Mean (95%CI) | 6 | 9 (2; 28) | 6 | 3538 (2; 7153) | 0.053a |
| Median [Q1–Q3] | 2 [2; 2] | 3195 [431; 4907] | 0.028* | |||
Anti-RBD IgG were measured in samples taken 76 and 99 days (median) after third and fourth vaccines, respectively, by Chemiluminescent Microparticle ImmunoAssay (CMIA) SARS-CoV-2 IgG II Quant (Abbott, IL, USA), expressed as binding antibody units (BAU) per ml. Neutralization capacity [NT50] is expressed as a function of reciprocal values of sera dilutions. WT = wild type Wuhan stain; BA.1 = Omicron variant. *Wilcoxon signed ranks test; aPaired samples t-test; Median [Q1;Q3].