OBJECTIVE: We aimed to investigate if patients with rheumatic diseases treated with rituximab raise a serological response towards the COVID-19 mRNA vaccines and to elucidate the influence of time since the last dose RTX before vaccination on this response.
METHODS: We identified and included 201 patients with rheumatic diseases followed at the out-patient clinic at the Department of Rheumatology, Aarhus University Hospital, who had been treated with RTX in the period 2017-2021 and who had finished their two-dose vaccination with a COVID-19 mRNA vaccine. Total antibodies against SARS-CoV2 spike protein were measured on all patients and 44 blood donors as a reference.
RESULTS: We observed a time-dependent increase in antibody response as the interval from the last RTX treatment to vaccination increased. Only 17.3% of patients developed a detectable antibody response after receiving their vaccination 6 months or less after their previous RTX treatment. Positive antibody response increased to 66.7% in patients who had RTX 9-12 months before vaccination. All blood donors (100%) had detectable antibodies after vaccination.
CONCLUSION: Patients with rheumatic diseases treated with rituximab have a severely impaired serological response towards the COVID-19 mRNA vaccine. Our data suggest that the current recommendations of a 6 months interval between rituximab treatment and vaccination should be revised.