Table 5.
Characterization of individuals in Q4 versus Q1–3
| Characteristics | Q4 | Q1-3 | p-value1: Q4 vs Q1–3 | |
|---|---|---|---|---|
| Univariable | Multivariable | |||
| n | 25 | 144 | ||
| M/F | 6/19 | 28/116 | 0.8 | |
| Age (years), median (IQR) | 48 (40.5; 58.5) | 50.5 (42.0; 57.0) | 0.5 | |
| BMI (ratio), median (IQR) | 23.1 (21.5; 27.5) | 23.6 (21.7; 26.8) | 1.0 | |
| Comorbidities (n, %) | 5 (20.0%) | 62 (43.1%) | 0.03 | 0.03 |
| HCWs (n, %) | 2 (8.0%) | 36 (25.0%) | 0.07 | 0.18 |
| Time between last dose and questionnaire (days), median (IQR) | 90.0 (76; 108) | 101.0 (86.0; 112.5) | 0.22 | |
| Time between D2 and sampling (days), median (IQR) | 160.0 (107.5; 203.5) | 186.5 (154.0; 225.0) | 0.02 | 0.1 |
| Current number of vaccine doses, median (IQR) | 3 (22, 88.0%) | 3 (125, 86.8%) | 1.0 | |
| Anti-SP IgG (BAU/mL), median (IQR) | 414.0 (311.0; 766.0) | 124.0 (67.0; 221.0) | < 0.0001 | |
| Neutralization of Wuhan variant, median (IQR) | 8.5 (5.5; 12.7) | 2.8 (1.5; 6.3) | < 0.0001 | |
| Neutralization of Alpha variant, median (IQR) | 6.6 (5.3; 10.2) | 2.3 (1.2; 4.8) | < 0.0001 | |
| Neutralization of Delta variant, median (IQR) | 6.9 (5.8; 11.9) | 2.6 (1.3; 5.1) | < 0.0001 | |
| SARS-CoV-2 specific T cell response (IU/mL), median (IQR) | 0.79 (0.49; 1.1) | 0.19 (0.08; 0.33) | < 0.0001 | |
| Unspecific T cell stimulation (IU/ml), median (IQR) | 100.0 (20.0; 245.0) | 165.0 (26.0; 378.0) | 0.39 | |
Participants were divided into four quartiles depending on their level of anti-SP IgG (above or below the threshold of 244 BAU/mL) and IFNγ (above or below the threshold of 0.285 IU/mL). None of the participants with both values above the threshold (Q4) was infected after M12, while in the Q1, Q2, and Q3, the participants had values of either anti-SP IgG and/or IFNγ below the threshold, and some of them got infected after M12
N number; IQR interquartile range; HCW health care workers; Anti-SP anti-Spike; IgG immunoglobulin G; Anti-N anti-nucleocapsid
*p < 0.05, **p < 0.005, ***p < 0.0005, ****p < 0.00005
1Mann-Whitney test for quantitative variables; Fisher’s exact test for qualitative variables. All tests are two-sided with statistical significance p < 0.05. To identify infection and bad vaccine responder’s predictive factors, all variables with p < 0.15 in unadjusted analysis were used for multivariable logistic regression models