Background/Purpose:
COVID-19 vaccination can trigger a range of inflammatory and auto-immune phenomena, potentially including AAV. There are several international case reports of de novo and relapsed AAV following primary and booster vaccines, though few reports from Australia. Our study assessed the rate of new-onset and relapses of ANCA-associated vasculitis following COVID-19 vaccination, within our Sydney Local Health District of approximately 1 million people.

Methods: All patients admitted between February 2018 and July 2022, with the diagnosis of AAV (Granulomatosis with Polyangiitis or Microscopic Polyangiitis) were included. Patients were classified as de novo if they fulfilled the 2022 American College of Rheumatology classification criteria. Patients were classified as relapsed if they presented with symptoms included in the Birmingham Vasculitis Activity Score (BVAS) and their dose of corticosteroids was increased. The pre-vaccination period was defined as February 2018 to February 2021 (37 months), the post-vaccination period was defined as March 2021 to August 2022 (18 months). The rate of AAV cases was calculated using the Poisson count method and adjusted for exposure time.

Results: There were 75 cases of AAV between February 2018 and August 2022, with 51 during the pre-vaccine period and 24 during the post-vaccine period. The case rate of AAV in the pre-vaccination period was 1.44 cases/million/month, and 1.36 cases/million/month in the post-vaccination period. The rate ratio was 0.95 (95% CI 0.56 to 1.57, p = 0.93). There was no significant difference between the characteristics of patients who presented with AAV within 4 weeks of vaccination.

Conclusion: There was no significant increase in the rate of AAV presentations following vaccination within our Sydney Local Health District.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-impact-of-covid-19-vaccination-on-anca-vasculitis-hospitalisations-a-perspective-from-sydney-australia/