Table 4

SARS-CoV-2 IgG titre decay rates in IMID versus controls

Days for SARS-CoV-2 Ab titre to reach 7.0 U/mLDays for SARS-CoV-2 Ab titre to reach 0 U/mLChange after 90 days (%)Slope coefficient
95% CIP value
AZ vaccine
csDMARD IgG titre=1.05–0.0034 (days after second vaccination) R∧2=2.8%68.3308.850.53−0.010 to 0.0030.313
bDMARD IgG titre=1.29–0.0062 (days after second vaccination) R∧2=9.0%71.8208.172.31−0.012 to −0.000060.048
tsDMARD IgG titre=1.37–0.0082(days after second vaccination) R∧2=17.3%64.0167.181.70−0.013 to −0.0030.001
Pfizer vaccine
csDMARD IgG titre=1.55–0.0038(days after second vaccination) R∧2=9.2%185.5407.954.51−0.0078 to 0.00010.061
bDMARD IgG titre=1.56–0.0052(days after second vaccination) R∧2=20.7%137.5300.065.96−0.0078 to −0.00260.000
tsDMARD IgG titre=1.97–0.0097(days after second vaccination) R∧2=46.3%116.0203.186.61−0.013 to −0.0070.000
AZ vaccine control
IgG titre=1.51–0.0107(days after second vaccination) R∧2=30.9%62.1141.189.12−0.0152 to −0.0060.000
Pfizer vaccine control
IgG titre=1.60–0.0036(days after second vaccination) R∧2=13.2%209.7444.452.57−0.006 to −0.00070.013
  • Bold values are significant with p-value <0.05.

  • DMARD, disease-modifying antirheumatic therapy; IMID, immune-mediated inflammatory diseases; tsDMARD, targeted synthetic DMARD.