Anti-SARS-CoV-2 spike antibody titers and neutralizing antibodies in vaccinated rheumatoid arthritis patients.

Objectives: Coronavirus Disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A serological test is used to assess the efficacy of vaccination. It has been reported that anti-SARS-CoV-2 spike (S) and neutralizing antibody (Ab) levels are lower following vaccination in patients with rheumatic disease. Here, we investigated anti-SARS-CoV-2 S and neutralizing Abs in vaccinated rheumatoid arthritis (RA) patients in Japan. Methods: : Anti-SARS-CoV-2 S and neutralizing Abs were quantified in 101 RA patients and 117 controls. Results: : Anti-SARS-CoV-2 S Ab levels were lower in RA patients than both earlier after vaccination in controls (mean RA 324.1±591.8 SDM-vs.-control 1216.6±854.4 U/ml, P =8.02X10 -16 ) and later after vaccination (324.1±591.8 -vs.582.0±415.6, P =0.0002). The interval between vaccination of the RA patients and serum collection was longer than for controls early after vaccination (142.1±31.6-vs.-98.3±11.2, P =6.54X10 -32 ), but shorter than the later sample from the controls (142.1±31.6-vs.-257.3±11.2, P =1.79X10 -94 ). Importantly, anti-SARS-CoV-2 neutralizing Ab titers in RA patients were higher than in either early or later control samples (10.7±4.9-vs.-8.6±6.6%, P =0.0072, and 10.7±4.9-vs.-3.1±3.7%, P =1.04X10 -28 , respectively). Conclusion: Anti-SARS-CoV-2 S Ab titers in vaccinated RA patients were lower than in controls, but anti-SARS-CoV-2 neutralizing Ab levels were higher.