Data on anti-S1/S2 IgG seroconversion rates, anti-SARS-CoV-2 S1/S2 IgG GMT, FI-GMT in titres, frequency of NAb and median percentage of neutralising activity in MTX-hold and MTX-maintain groups at baseline (D0) and after first (D28) and second (D69) dose of vaccine
| After first dose (D28) | After second dose (D69) | |||||
| MTX-hold (n=47) | MTX-maintain (n=55) | P value | MTX-hold (n=37) | MTX-maintain (n=55) | P value | |
| Anti-S1/S2 IgG | ||||||
| Seroconversion, n (%) | 10 (21.3) | 2 (3.6) | 0.011 | 29 (78.4) | 30 (54.5) | 0.019 |
| GMT | 5.7 (4.3–7.5) | 2.8 (2.3–3.5) | 0.002 | 34.2 (25.2–46.4) | 16.8 (11.9–23.6) | 0.003 |
| FI-GMT | 2.9 (2.2–3.7) | 1.4 (1.1–1.7) | <0.001 | 17.1 (12.6–23.1) | 8.1 (5.8–11.4) | 0.007 |
| Neutralising antibodies | ||||||
| NAb positivity, n (%) | 11 (23.4) | 4 (7.3) | 0.027 | 23 (62.2) | 27 (49.1) | 0.217 |
| Neutralising activity | 41.7 (37.0–46.0) | 57.7 (51.8–65.9) | 0.133 | 53 (42–68.8) | 51.7 (37.8–62.2) | 0.335 |
MTX-hold: baseline seronegative patients randomised to interrupt MTX after the first and second dose (n=47 at D28 and n=37 at D69 due to 10 patients who flared at D28 and did not withdraw MTX-twice). MTX-maintain: baseline seronegative patients randomised to maintain methotrexate stable throughout the study and who adhered to the protocol (n=69).
Seroconversion (SC) is defined as postvaccination titre ≥15 AU/mL by Indirect ELISA (LIAISON SARS-CoV-2 S1/S2 IgG). Positivity for NAb was defined as neutralising activity ≥30% (cPass sVNT Kit). Frequencies of subjects with SC or positive NAb are presented as number (%) and were compared using a two-sided χ2 test at prespecified time points (D28 and D69).
IgG antibody titres and FI-GMT are expressed as GMT with 95% CI. Data on IgG titres were analysed in logarithm-transformed data using generalised estimating equations with normal marginal distribution and gamma distribution, respectively, and identity binding function assuming first-order autoregressive correlation matrix between moments in the comparison of the two groups, followed by Bonferroni’s multiple comparisons.
Percentages of neutralising activity among subjects with positive NAb are expressed as median (IQR). FI-GMT and neutralising activity were compared using a two-sided Mann-Whitney U test for comparison between the two groups, at prespecified time points (D28 and D69). All analyses were two-sided.
D28, day 28; D69, day 69; FI-GMT, factor increase of geometric mean titre; GMT, geometric mean titre; MTX, methotrexate; NAb, neutralising antibody; RA, rheumatoid arthritis.