Table 4. Characteristic times for the waning antibodies.
| Group | Antibody | T50 in days (IQR) | T90 in days (IQR) | Estimated % relative loss between T2 and T3 |
|---|---|---|---|---|
| 1 (n = 74) | RBD | 50 (42–58) | 168 (140–193) | 87% (82–91) |
| S1 | 53 (45–68) | 177 (149–227) | 86% (77–90) | |
| S2 | 86 (59–123) | 287 (197–309) | 69% (56–81) | |
| 2 (n = 9) | RBD | 55 (48–61) | 182 (160–203) | 84% (76–86) |
| S1 | 49 (46–65) | 164 (153–214) | 84% (71–89) | |
| S2 | 37 (37–51) | 122 (121–168) | 92% (71–94) | |
| 3 (n = 6) | RBD | 84 (62–102) | 278 (205–340) | 71% (64%– 82%) |
| S1 | 82 (78–91) | 272 (258–302) | 72% (68%– 74%) | |
| S2 | 122 (94–155) | 404 (312–514) | 58% (49%– 67%) |
The half-life T50 (T90) equals the number of days at which there is 50% (10%) left from the estimated DF50 at time zero assuming an exponential decay. The estimated % relative loss is calculated as [DF50(T2)—DF50(T3)) / DF50(T2). We compared specific antibodies between groups 1 and 2 using a Wilcoxon rank sum test: RBD, p = 0.330; S1, p = 0.855: S2, p = 0.001.