medwireNews: A third dose of the Pfizer–BioNTech (BNT162b2) vaccine gives rise to a neutralizing antibody response in the majority of people with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, but those treated with rituximab are unlikely to respond, researchers report.
The study included 21 patients on immunosuppressive maintenance therapy regimens involving combinations of steroids, azathioprine, mycophenolate mofetil, and rituximab, who received two doses of the BNT162b2 vaccine between March and May 2021, with a third dose given a median 103 days after the second.
Claudius Speer (University Hospital Heidelberg, Germany) and team say that the third dose “induced a strong neutralising antibody activity against B.1.617.2 in most individuals.” In the overall study population, the proportion of patients with neutralizing antibodies against the B.1.617.2 (delta) variant of SARS-CoV-2 increased from 38% at a median of 23 days after their second vaccine dose to 57% at a median of 21 days after the third dose.
The researchers note, however, that none of the eight people treated with rituximab within the past year had detectable levels of these antibodies, compared with 92% of the 13 patients who had not been treated with rituximab.
These findings are in agreement with previous studies showing “particularly low seroconversion rates” following COVID-19 vaccination in rituximab-treated patients, they write in a letter to the Annals of the Rheumatic Diseases.
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group
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Ann Rheum Dis 2022; doi:10.1136/annrheumdis-2021-221747