Vaccination for COVID-19 was not associated with an increased risk of severe multiple sclerosis (MS) relapse according to results from a recent self-controlled case series study published in Neurology.

The study included 124,545 people with MS from the French National Health Data System, including individuals who had experienced MS relapses requiring treatment with high-dose corticosteroids. Overall, 82% of the identified patients had received at least 1 dose of a COVID-19 vaccine.

Researchers then evaluated risk of MS relapse associated with COVID-19 vaccination in the initial 45 days after vaccination and after 1, 2, or 3 booster doses. They found that the combined incidence rate ratio (IRR) for experiencing a relapse was 0.97 (0.91-1.03, P=0.30), and nearly all participants showed no increased risk of relapse, including in those who were aged <50 years and those who had an MS diagnosis for <10 years. Individuals who had relapsed at least twice in the previous 2 years, particularly those who were untreated, did experience a slightly increased relapse risk after a booster dose (IRR 1.39 [1.08–1.80]).

“Our findings are reassuring that these vaccines can be used without any worry about the risk of relapse,” said Study Author Xavier Moisset, MD, PhD, of Clermont Auvergne University in Clermont-Ferrand, France. “The absence of such a risk is encouraging for people with MS that they may receive booster shots when needed, especially if booster shots are to be repeated in the future.”

Source: Moisset X, Leray E, Chenaf C, et al. Risk of Relapse After COVID-19 Vaccination Among Patients With Multiple Sclerosis in France: A Self-Controlled Case Series. Neurology. 2024;103(5):e209662. doi:10.1212/WNL.0000000000209662