Comparison of SARS-COV-2 humoral response between rheumatoid arthritis, psoriatic arthritis and spondyloarthritis patients and controls in two unvaccinated cohorts

Objective To compare the humoral response after a SARS-CoV-2 infection in an inflammatory rheumatic disease population with a healthy control population in a case-control study. Methods Cases: between March and September 2021, all consecutive unvaccinated patients followed for rheumatoid arthritis (RA), spondyloarthritis (SpA) or psoriatic arthritis (PsA) in 16 hospitals in France were systematically screened with a SARS-CoV-2 serological test. Patients with a positive test were included in the COVID-RIC-2 cohort. Controls: between June and July 2020, healthcare professionals working in the Toulouse University Hospital were screened with a SARS-CoV-2 serological test. Those with apositive test were included in the COVID-BIOTOUL cohort and matched to those from COVID-RIC-2 by age, sex and time-sampling on infection date. Analyses: total SARS-CoV-2 antibody titres were centrally measured and compared. Results 95 patients from COVID-RIC-2 (mean age 49 years, 76% females, median delay of COVID infection: 149 days) including 48 RA, 33 SpA and 14 PsA were compared to 95 matched controls. Globally, there was no significant difference of SARS-CoV-2 antibody titres between both populations: 155 Binding Antibody Units (BAU) (IQR:7-376) in COVID-RIC-2 vs. 120 BAU (IQR:35-320) in COVID-BIOTOUL. There was a trend towards higher antibody titres in patients from COVID-RIC-2 with severe COVID-19 symptoms. In COVID-RIC-2, there was no impact of age, sex, time-sampling or underlying disease on antibody titres and patients taking glucocorticoids, abatacept or rituximab trended toward having lower antibody titres after COVID-19 infection. Conclusion This study provides reassuring data on humoral response after COVID-19 infection in patients treated with disease-modifying anti-rheumatic drugs.