Table 1.
Anti-spike IgG titers and adverse reactions after the primary series, monovalent booster, and bivalent booster.
| Primary series (N = 296) | Monovalent booster (N = 317) | Bivalent booster (N = 114) | p-value | ||
|---|---|---|---|---|---|
| Participant background | |||||
| Age, median (IQR, range) | 40 (30.5–47.5, 20–70) | 41 (33–48, 21–71) | 43 (35–49, 20–69) | 0.142 | |
| Sex (female, %) | 221 (74.7) | 231 (72.9) | 87 (76.3) | 0.745 | |
| Previous SARS-CoV-2 infection (%) | 0 (0) | 8 (2.5) | 47 (41.2) | < 0.001 | |
| Anti-spike IgG titers | |||||
| Before vaccination, GMT (95 % CI), AU/mL | − | 589 (543–640) | 5,506a (4,257–7,119) | < 0.001b | |
| After vaccination, GMT (95 % CI), AU/mL | 9,093 (8,393–9,849) | 16,971 (15,700–18,340) | 24,871 (21,558–28,695) | < 0.001 | |
| Local reactions (%) | |||||
| Pain at injection site | 278 (93.9) | 314 (99.1) | 110 (96.5) | 0.002 | |
| Redness | 61 (20.6) | 109 (34.4) | 27 (23.7) | < 0.001 | |
| Swelling | 122 (41.2) | 151 (47.6) | 46 (40.4) | 0.198 | |
| Systemic reactions (%) | |||||
| Fever | ≥ 38.0°C | 65 (22.0) | 83 (26.2) | 14 (12.3) | 0.009 |
| Duration, mean (95 % CI), days | 0.25 (0.19–0.31) | 0.31 (0.25–0.38) | 0.12 (0.06–0.18) | 0.003 | |
| Fatigue | 247 (83.5) | 269 (84.9) | 90 (79.0) | 0.347 | |
| Headache | 189 (63.9) | 215 (67.8) | 67 (58.8) | 0.202 | |
| Chills | 146 (49.3) | 167 (52.7) | 45 (39.5) | 0.054 | |
| Vomiting | N/A | 12 (3.8) | 3 (2.6) | 0.768b | |
| Diarrhea | 38 (12.8) | 40 (12.6) | 8 (9.3) | 0.222 | |
| Muscle Pain | 175 (59.1) | 271 (85.5) | 81 (71.1) | < 0.001 | |
| Joint Pain | 142 (48.0) | 172 (54.3) | 45 (39.5) | 0.021 | |
| Antipyretic use | |||||
| Before vaccination | 1 (0.3) | 20 (6.3) | 8 (7.0) | < 0.001 | |
| After vaccination | 152 (51.4) | 146 (46.1) | 56 (49.1) | 0.422 | |
IQR; inter-quartile range, GMT; geometric mean titer, CI; confidence interval, N/A; not available.
a
Data on the IgG titers before the bivalent booster were available from 86 participants.
b
Comparison between the monovalent and bivalent boosters.