Table 2

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 valueMTX-hold (n=37)MTX-maintain (n=55)P value
Anti-S1/S2 IgG
Seroconversion, n (%)10 (21.3)2 (3.6)0.01129 (78.4)30 (54.5)0.019
 GMT5.7 (4.3–7.5)2.8 (2.3–3.5)0.00234.2 (25.2–46.4)16.8 (11.9–23.6)0.003
 FI-GMT2.9 (2.2–3.7)1.4 (1.1–1.7)<0.00117.1 (12.6–23.1)8.1 (5.8–11.4)0.007
Neutralising antibodies
NAb positivity, n (%)11 (23.4)4 (7.3)0.02723 (62.2)27 (49.1)0.217
Neutralising activity41.7 (37.0–46.0)57.7 (51.8–65.9)0.13353 (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.