Background: Vaccination against influenza has been suggested to induce relapses of ANCA-associated vasculitis but evidence is lacking. In this study, we assessed whether vaccination against influenza increases the occurrence of relapses in patients with ANCA-associated vasculitis.
Methods: Two hundred and thirty consecutive patients with ANCA-associated vasculitis from our out-patient clinics of a tertiary referral center, with at least 1 year of follow-up, were included. Retrospectively, the relapse rate per 100 patients at risk in patients who had been vaccinated against influenza within the preceding year and in patients who not had been vaccinated within that time period were calculated.
Results: The relapse rate per 100 patients at risk was lower in patients who had been vaccinated against influenza (3.4) than in patients who had not been vaccinated (6.3), when analyzed for the entire year and for every quarter of the year. Also, the disease-free survival per separate year according to the vaccination status was lower in all 5 years in patients who had been vaccinated, being statistically significant in 2 years.
Conclusion: Vaccination against influenza does not increase the relapse rate in patients with ANCA-associated vasculitis.