Bivariate comparisons between patients who were seronegative and seropositive to the COVID-19 booster by characteristics and demographics.
| Value | Negative | Positive | P* | |
|---|---|---|---|---|
| N | 31 | 10 | 21 | |
| Age, mean (SD) | 61.5 (16.7) | 62.3 (14.0) | 61.0 (18.1) | 0.85 |
| Age, median (IQR) | 64 (51-72) | 63 (51-69) | 65 (51-73) | 0.75 |
| Sex, n (%) | > 0.99 | |||
| Female | 23 (74) | 7 (70) | 16 (76) | |
| Male | 8 (26) | 3 (30) | 5 (24) | |
| Race, n (%) | 0.49 | |||
| White | 27 (87) | 8 (80) | 19 (90) | |
| Black or African American | 1 (3) | 1 (10) | 0 (0) | |
| Asian | 3 (10) | 1 (10) | 2 (10) | |
| RA, n (%) | 4 (13) | 1 (10) | 3 (14) | > 0.99 |
| Sjögren syndrome, n (%) | 5 (16) | 2 (20) | 3 (14) | > 0.99 |
| SSc, n (%) | 3 (10) | 1 (10) | 2 (10) | > 0.99 |
| GPA, n (%) | 14 (45) | 5 (50) | 9 (43) | > 0.99 |
| PMR, n (%) | 1 (3) | 0 (0) | 1 (5) | > 0.99 |
| IgG4 disease, n (%) | 1 (3) | 1 (10) | 0 (0) | 0.32 |
| MPA, n (%) | 2 (6) | 0 (0) | 2 (10) | > 0.99 |
| IgG levels around booster dose, mg/dL,median (IQR) | 757 (656-963) | 689 (651-757) | 928 (735-1001) | 0.02 |
| IgG levels around booster dose, n (%) | 0.32 | |||
| < 400 mg/dL | 1 (3) | 1 (10) | 0 (0) | |
| < 700 mg/dL | 9 (29) | 5 (50) | 4 (19) | |
| Absolute lymphocyte levels around booster dose, median (IQR) | 1.6 (1.3-1.9) | 1.4 (1.1-1.7) | 1.7 (1.4-1.9) | 0.21 |
| Antirheumatic therapies other than RTX | ||||
| Any immunosuppressant, n (%) | 9 (29) | 3 (30) | 6 (29) | > 0.99 |
| LEF | 1 (3) | 0 (0) | 1 (5) | > 0.99 |
| AZA | 1 (3) | 1 (10) | 0 (0) | 0.32 |
| MTX | 3 (10) | 2 (20) | 1 (5) | 0.24 |
| MMF | 3 (10) | 0 (0) | 3 (14) | 0.53 |
| TCZ | 1 (3) | 0 (0) | 1 (5) | > 0.99 |
| CS, n (%) | 5 (16) | 1 (10) | 4 (19) | > 0.99 |
| Prednisone dose, mg, median (IQR) | 4.8 (4.0-5.5) | 5.0 (5.0-5.0) | 4.5 (3.5-6.0) | 0.65 |
| First vaccine series type, n (%) | 0.29 | |||
| Pfizer | 18 (58) | 8 (80) | 10 (48) | |
| Moderna | 11 (35) | 2 (20) | 9 (43) | |
| J&J | 1 (3) | 0 (0) | 1 (5) | |
| Sinovac | 1 (3) | 0 (0) | 1 (5) | |
| Third vaccine dose type, n (%) | 0.24 | |||
| Pfizer | 19 (61) | 8 (80) | 11 (52) | |
| Moderna | 12 (39) | 2 (20) | 10 (48) | |
| Dichotomous B cell status around booster dose, n (%) | < 0.001 | |||
| No detectable B cells | 7 (23) | 7 (70) | 0 (0) | |
| Detectable B cells | 22 (71) | 2 (20) | 20 (95) | |
| Missing | 2 (6) | 1 (10) | 1 (5) | |
| RTX for remission induction, n (%) | 2 (6) | 0 (0) | 2 (10) | > 0.99 |
| Time from last RTX infusion to booster, days, median (IQR) | 260 (216-379) | 188 (169-245) | 301 (251-368) | 0.03 |
| Time from last RTX infusion to booster dose, months, n (%) | 0.10 | |||
| < 6 | 8 (26) | 5 (50) | 3 (14) | |
| 6-12 | 15 (48) | 3 (30) | 12 (57) | |
| > 12 | 8 (26) | 2 (20) | 6 (29) | |
↵* P values are from Fisher exact tests, t tests, and Wilcoxon rank sum tests. AZA: azathioprine; CS: corticosteroid; COVID-19: coronavirus disease 2019; GPA: granulomatosis with polyangiitis; LEF: leflunomide; MMF: mycophenolate mofetil; MPA: microscopic polyangiitis; MTX: methotrexate; PMR: polymyalgia rheumatica; RA: rheumatoid arthritis; RTX: rituximab; SSc: systemic sclerosis; TCZ: tocilizumab.