TNF and COVID-19: After the second dose of COVID-19 vaccination, the seropositivity rate and the anti-SARS-CoV-2 IgG level in RA patients was both uplifted to a large extent, except for the seropositivity rate in RA patients receiving non-anti-TNF-α bDMARDs, compared with those receiving csDMARDs (77.4% vs. 100%, p=0.006).