Avouac J, Miceli-Richard C, Combier A, et al. - Researchers investigated the factors affecting the humoral response to COVID-19 vaccination in patients with inflammatory rheumatic diseases in maintenance therapy with RTX.

• Observational prospective usual care study of RTX-treated patients.

• A two-dose regimen COVID-19 vaccination was received by all patients.

• Assessment of serum IgG antibody levels against SARS-CoV-2 spike proteins at the time of the new RTX infusion revealed induction of antibodies reaching the assay cut-off value of 15 AU/m in 16/45 (36%) recruited patients.

• A negative serology was recorded in 29/45 (64%) patients.

• Within RTX treated patients, undetectable B cells were recorded in 25 (56%) patients.

• In RTX treated patients, the main independent contributing factor of antibody response to SARS-COV-2 vaccination was B cell depletion.

• Researchers support monitoring CD19 to recognize the most suitable period to perform vaccination.