Correspondence on 'SARS-CoV-2 vaccination in rituximab-treated patients: evidence for impaired humoral but inducible cellular immune response'.

We read with a great interest the article published by Bonelli et al suggesting an inducible cellular immune response in rituximab (Rtx) treated patients.1 The CD20-antibody Rtx is one of the most widespread biologicals worldwide with a broad spectrum of oncological and rheumatological indications. Due to its depleting effect on circulating B cells, the generation of antibodies against novel pathogens is impaired in Rtx-treated patients.2 3 Accordingly, the last EULAR recommendations on vaccination advised that ‘vaccination should be provided at least 6 months after the last administration and 4 weeks before the next course of B cell-depleting therapy’.4 To ensure appropriate SARS-CoV-2 vaccination, the last EULAR advise was to refer to a rheumatologist.5 The American College of Rheumatology (ACR) has recommended to vaccinate Rtx-treated patients not earlier than 5 months after the last administration with the next cycle given not earlier than 2–4 weeks thereafter.6 In any case, the combination of B cell-depleting therapy with vaccination has been quite a challenge for patients and physicians—especially since it became clear that Rtx therapy may be associated with unfavourable outcomes in B cell-depleted patients.7 Fortunately, very recent data by Bonelli et al have now suggested that a cellular response is mounted after SARS-CoV-2 vaccination in Rtx-treated patients despite a failed humoral immune response.1 The authors demonstrated that peripheral blood cells of vaccinated patients do produce Interferon γ (IFNγ) after stimulation with SARS-CoV-2 spike (S) protein-derived overlapping peptides.1 These results increase the scientific interest into a more detailed characterisation of vaccine-reactive T-cell immunity, which has recently been in the focus of our group as well due to a frequent Rtx application in our settings. Applying multiparameter flow cytometry, we explored the …