The use of inactivated SARS-CoV-2 vaccines does not appear to increase the risk of relapse for patients with neuromyelitis optica spectrum disorder (NMOSD) or multiple sclerosis (MS), according to a study published in Multiple Sclerosis and Related Disorders.

No statistical difference was found between the rate of acute relapses between patients with NMOSD or MS who received the vaccine and propensity score (PS)-matched unvaccinated patients.

After the first dose of the vaccine, 10 patients with NMOSD (9.2%) and 4 patients with relapsing-remitting MS (RRMS; 5.1%) experienced acute relapses. In comparison, 15 patients with NMOSD (6.9%) who were unvaccinated and 12 patients with RRMS (7.7%) who were unvaccinated experienced acute relapses.

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Relapses occurred as early as 3 days after vaccination and as late as 7 months after, with a peak in relapses occurring between 1 and 3 months after vaccination. Patients were followed for a median of 9.3 months for NMOSD and 9.4 months for RRMS.

At least 1 adverse event was experienced within the first 3 days for 18 patients with NMOSD (16.5%) and 21 patients with RRMS (26.9%). Local pain at the injection site was the most commonly reported early reaction, and fatigue and numbness were the most common systemic reactions.

“Our results indicate that inactivated SARS-CoV-2 vaccines are safe for patients with CNS demyelinating diseases and do not appear to increase the risk of relapse within a median of 9-month follow-up,” the authors concluded. “Although our results should be interpreted with caution, it provides useful information for further vaccination initiatives.”

The study also found that 77.6% of patients with NMOSD and RRMS who responded to questionnaires had a low intention of getting vaccinated, mainly due to concerns about relapse (59%) or adverse events (10%). Of these patients, 28% were informed by healthcare workers that vaccination was not recommended.

A total of 556 patients with NMOSD and 280 patients with RRMS were included in the questionnaire study between June 2021 and September 2021. Inactivated SARS-CoV-2 vaccines were received by 109 patients with NMOSD and 78 patients with RRMS in the study.


Kong L, Wang X, Chen H, et al. Relapses after SARS-CoV-2 vaccination in patients with neuromyelitis optica spectrum disorder and multiple sclerosis. Mult Scler Relat Disord. 2022;68(104167):104167. doi:10.1016/j.msard.2022.104167