Comorbidity status of the study population according to the peak anti-spike IgG levels post-second vaccination
| Total (n=1635) | Peak antibody levels >700 AU/mL (n=1555) | Peak antibody levels 50–700 AU/mL (n=75) | Peak antibody levels <50 AU/mL (n=5) | Peak antibody levels 14–84 days post-second vaccination (AU/mL) | P value | ||
| Median | IQR | ||||||
| Comorbidity | 0.009 | ||||||
| No | 872 (100.0%) | 830 (95.2%) | 42 (4.8%) | 0 (0.0%) | 11 681 | 4362–23 299 | |
| Yes | 763 (100.0%) | 725 (95.0%) | 33 (4.3%) | 5 (0.7%) | 9637 | 3493–19 750 | |
| Smoking | 106 (100.0%) | 99 (93.4%) | 7 (6.6%) | 0 (0.0%) | 7588 | 1828–19 639 | 0.003 |
| Pregnant | 23 (100.0%) | 23 (100.0%) | 0 (0.0%) | 0 (0.0%) | 14 684 | 8199–19 453 | 0.6 |
| Asthma | 316 (100.0%) | 300 (94.9%) | 16 (5.1%) | 0 (0.0%) | 10 161 | 4296–19 559 | 0.2 |
| Hypertension | 176 (100.0%) | 168 (95.5%) | 8 (4.5%) | 0 (0.0%) | 8770 | 3272–18 746 | 0.01 |
| Thyroid disorder (excluding malignancy) | 137 (100.0%) | 128 (93.4%) | 9 (6.6%) | 0 (0.0%) | 10 395 | 3280–25 672 | 0.9 |
| Diabetes | 95 (100.0%) | 89 (93.7%) | 5 (5.3%) | 1 (1.1%) | 8748 | 2950–19 346 | 0.04 |
| Immunosuppression | 80 (100.0%) | 68 (85.0%) | 7 (8.8%) | 5 (6.2%) | 7451 | 1503–17 695 | 0.002 |
| Psoriasis | 48 (100.0%) | 43 (89.6%) | 5 (10.4%) | 0 (0.0%) | 7435 | 2573–13 850 | 0.06 |
| Heart disease | 34 (100.0%) | 32 (94.1%) | 2 (5.9%) | 0 (0.0%) | 13 925 | 4999–22 430 | 0.7 |
| Non-haematological malignancy | 41 (100.0%) | 40 (97.6%) | 1 (2.4%) | 0 (0.0%) | 13 159 | 9261–23 955 | 0.3 |
| Rheumatological disorder | 27 (100.0%) | 24 (88.9%) | 2 (7.4%) | 1 (3.7%) | 5691 | 1770–15 567 | 0.05 |
| Respiratory disease (excluding asthma) | 37 (100.0%) | 33 (89.2%) | 4 (10.8%) | 0 (0.0%) | 6993 | 2302–12 927 | 0.01 |
| Haematological disease (excluding malignancy) | 36 (100.0%) | 35 (97.2%) | 1 (2.8%) | 0 (0.0%) | 12 236 | 6738–20 060 | 1 |
| Liver disease | 11 (100.0%) | 11 (100.0%) | 0 (0.0%) | 0 (0.0%) | 11 419 | 5818–13 705 | 0.4 |
| Neurological disorder | 12 (100.0%) | 12 (100.0%) | 0 (0.0%) | 0 (0.0%) | 6035 | 5258–12 886 | 0.3 |
| CKD stage 3, 4 or 5 | 6 (100.0%) | 5 (83.3%) | 0 (0.0%) | 1 (16.7%) | 10 129 | 5672–17 965 | 0.7 |
| Lupus | 7 (100.0%) | 5 (71.4%) | 1 (14.3%) | 1 (14.3%) | 1478 | 695–13 582 | 0.1 |
| Splenic disorder (excluding traumatic splenectomy) | 4 (100.0%) | 4 (100.0%) | 0 (0.0%) | 0 (0.0%) | 1796 | 1040–9695 | 0.2 |
| Haematological malignancy | 3 (100.0%) | 3 (100.0%) | 0 (0.0%) | 0 (0.0%) | 7731 | 7230–16 186 | 0.9 |
| Organ transplant | 5 (100.0%) | 1 (20.0%) | 0 (0.0%) | 4 (80.0%) | 11 | 6–21 | <0.001 |
Bold indicates a significant p value of <0.05.
CKD, chronic kidney disease.