Risk of disease relapse, safety and tolerability of SARS-CoV-2 vaccination in patients with chronic inflammatory neuropathies

Background: To evaluate the risk of relapse after SARS-CoV-2 vaccination, and its safety and tolerability, in patients with chronic inflammatory neuropathies. Methods: In this multicenter, cohort, and case-crossover study, the risk of relapse associated with SARS-CoV-2 vaccination was assessed by comparing frequency of relapse in CIDP and MMN patients who underwent or did not undergo vaccination. Frequency of relapse in the three months prior and after vaccination, and safety and tolerability of SARS-CoV-2 vaccination were also assessed. Results: 336 patients were included (278 CIDP; 58 MMN). 307 (91 per cent) patients underwent SARS-CoV-2 vaccination. Twenty-nine patients (9 per cent) did not undergo vaccination. Mild and transient relapses were observed in 16 (5 per cent) patients (13 CIDP; 3 MMN) after SARS-CoV-2 vaccination and in none of the patients who did not undergo vaccination (RR= 3.21, 95 per cent CI, 0.19-52.25). There was no increase in the specific risk of relapse associated with type of vaccine or diagnosis. Comparison with the 3-month control period preceding vaccination revealed an increased risk of relapse after vaccination (RR= 4.00; 95per cent CI, 1.35-11.82), which was restricted to CIDP patients (RR= 3.25, 95per cent CI, 1.07-9.84). The safety profile of SARS-CoV-2 vaccination was characterized by short-term, mild-to-moderate local and systemic adverse events. Conclusions: SARS-CoV-2 vaccination in CIDP and MMN patients does not seem to be associated with an increased risk of relapse at primary endpoint, although a slightly increased risk in CIDP patients was found compared to the 3 months before vaccination.