Demographics and clinical characteristics of the study participants
| Diagnosis | SLE (n=71) | RA (n=29) |
| Mean age (years) | 39.0 (11.9) | 53.8 (9.3) |
| Gender, n (%) | ||
| Male | 3 (4.2) | 4 (13.8) |
| Female | 68 (95.8) | 25 (86.2) |
| Duration of illness (years) | 12.6 (8.6) | 3.7 (5.1) |
| Disease activity score | ||
| SLEDAI | 3.1 (2.7) | |
| DAS28-ESR | – | 3.5 (1.5) |
| CDAI for RA | – | 12.2 (12.7) |
| Antimalarial drug, n (%) | 50 (70.4) | 22 (75.9) |
| Immunosuppressive medication, n (%) | ||
| MMF | 49 (69.0) | – |
| Azathioprine | 10 (14.1) | – |
| Methotrexate | 4 (5.6) | 27 (93.1) |
| Calcineurin inhibitor | 5 (7.0) | 4 (13.8) |
| Leflunomide | – | 8 (27.6) |
| Anti-TNF | – | 2 (6.8) |
| Prednisolone | 63 (88.7) | 23 (79.3) |
| None | 2 (2.8) | 1 (3.4) |
| Immunosuppressive medication dose (mg/day) | ||
| MMF | 1181 (465) | – |
| Azathioprine | 65 (34) | – |
| Methotrexate | 9.4 (4.3) | 16.2 (5.6) |
| Tacrolimus | 2.5 (2.3) | – |
| Leflunomide | – | 84 (47) |
| Prednisone | 5.3 (2.8) | 8.5 (8.0) |
| Cyclosporine | 125 (35) | 110 (22) |
| Number of immunosuppressive medications used, n (%) | ||
| 0 | 2 (2.8) | 2 (6.9) |
| 1 | 13 (18.3) | 5 (17.2) |
| 2 | 51 (71.8) | 9 (31.0) |
| 3 | 4 (5.6) | 13 (44.8) |
| 4 | 1 (1.4) | 0 (0) |
| Overall immunosuppressive load (modified Vasudev score) | 2.71 (1.6) | 2.78 (2.1) |
| Initial vaccine regimen, n (%) | ||
| Inactivated/inactivated | 27 (38.0) | 6 (20.7) |
| AZD1222/AZD1222 | 26 (36.6) | 15 (51.7) |
| AZD1222/BNT162b2 | 18 (25.4) | 8 (27.6) |
| Interval between the second dose of initial vaccine and third BNT162b2 booster (days) | ||
| Inactivated/inactivated | 88 (31) | 94 (44) |
| AZD1222/AZD1222 | 43 (13) | 53 (17) |
| AZD1222/BNT162b2 | 56 (15) | 61 (11) |
| Prebooster anti-RBD IgG>2360 BAU/mL, n (%) | 2 (2.8) | 0 (0) |
Data expressed as mean (SD) unless otherwise indicated.
BAU, binding antibody unit; CDAI, Clinical Disease Activity Index; DAS28, Disease Activity Score using 28 joint counts; ESR, erythrocyte sedimentation rate; anti-RBD IgG, antispike receptor-binding domain IgG antibody; MMF, mycophenolate mofetil; RA, rheumatoid arthritis; RBD, receptor-binding domain; SLEDAI, Systemic Lupus Erythematosus Disease Activity Index; TNF, tumour necrosis factor.