For a study, researchers sought to determine if individuals with a rheumatic disease (RD) who were given rituximab (RTX) had a serological response to the coronavirus disease 2019 (COVID-19) mRNA vaccinations, and if so, how long it had been since the previous RTX dosage before vaccination affected this response.

They identified and included 201 patients with RDs who had been treated with RTX and had completed their 2-dose immunization series with a COVID-19 mRNA vaccine at the Department of Rheumatology, Aarhus University Hospital, between 2017 and 2021. All patients and 44 blood donors were tested for total antibodies against the SARS-CoV-2 spike protein.

As the period between the previous RTX treatment and vaccination extended, they saw an increase in antibody response. After getting their immunization in less than or around 6 months after their prior RTX treatment, just 17.3% of patients exhibited a measurable antibody response. Patients who received RTX 9-12 months before immunization reported a 66.7% increase in positive antibody response. After immunization, all blood donors (100%) exhibited detectable antibodies.

Patients with RDs who receive RTX show a significantly reduced serological response to COVID-19 mRNA vaccinations. The findings implied that the present 6-month delay between RTX therapy and immunization should be reconsidered.