This is one of the largest studies investigating the occurrence of disease flares and AEs in patients with SV following SARS-CoV-2 vaccination in a real-world setting.
It is well known that immunological stimuli, including vaccines administration may trigger, in limited cases, a disease flare up in patients with rheumatic diseases (12). The occurrence of disease flares in our cohort was very low with evidence of only one case out of 107 patients. Even though this flare was severe and the patient was hospitalized, he was discharged after one week in good clinical conditions. Our findings, together with the previous demonstration in GCA patients of no significant difference in the rate of flares between patients receiving vaccination for influenza virus and patients receiving vaccination for SARS-CoV-2 (13), look extremely encouraging. As in the general population a great efficacy of SARS CoV2 vaccination has been demonstrated (14.15), our data, along with previous evidence (13), support the safety of these vaccines in SV patients and further encourage their administration in the next future.
It is interesting to note that new cases of SV have been documented following anti-SARS-CoV2 vaccination. We had the opportunity to describe the onset of leukocytoclastic vasculitis following anti-SARS-CoV-2 vaccination with Vaxzevria-ChAdOx1-S (16) and there are a few case reports demonstrating the new appearance of ANCA-associated vasculitis as well as IgA vasculitis and GCA after the administration of anti-SARS-CoV-2 vaccines (17–21). These observations provide interesting insight on the pathogenesis of SV and will surely deserve further investigations in the next future.
In our study the frequency of AEs was similar between patients and controls and generally mild in all of them. In the SV group, no association was found between the ongoing immunosuppressive therapy and the risk of developing AEs. Consistent with our previous findings (22), and as reported in RCTs (14, 15), an inverse association between AEs occurrence and patients’ age has been detected. Specifically, a higher age appears as associated with a lower risk of developing AEs; this finding is not surprising as immunosenescence is known to contribute to a reduced vaccine response in older patients and, eventually, a lower occurrence of AEs (23).
Our findings are in line with previous studies demonstrating a low rate of disease flare and an overall good risk profile in patients with rheumatic diseases (8, 10, 13). Interestingly, in one of these studies a lower occurrence of disease flare up was observed in patients with connective tissue diseases and vasculitis compared to other rheumatic conditions such as inflammatory joint diseases (10). Thus, the similar tolerance profile of these vaccines between patients with SV and HCs, as well as the rarity of disease flares, is a reassuring result useful for physicians to encourage patients with SV to undergo vaccination. This topic is particularly relevant as a remarkable vaccine hesitancy has been documented in our patients during COVID-19 pandemic (24)
This study has some limitations, specifically, its retrospective nature did not allow to calculate the exact disease activity at the time of vaccination. However, as suggested by currently available recommendation on vaccine administration in patients with rheumatic diseases (25, 26), vaccines should be administered only in patients with inactive disease. As included SV patients were strictly monitored in our dedicated outpatient clinics, they were vaccinated only if the referring physician considered them in an inactive phase of disease.
Being SV a rare disease, strength of this study is represented by the large sample size. Additionally, its multicenter nature allowed us to include different types of SV referring to two major dedicated rare disease clinics in our country.