Individuals with multiple sclerosis (MS) face a heightened risk of severe COVID-19 infections; however, concerns about potential relapses following vaccination have persisted. A recent study published in the online edition of Neurology on August 14, 2024, indicates that the risk of relapse after COVID-19 vaccination for people with MS may not be as significant as previously thought.
Xavier Moisset, MD, Ph.D., from Clermont Auvergne University in Clermont-Ferrand, France, noted that the increased risk of severe COVID-19 in MS patients is often linked to their level of motor disability or their treatment regimens that may compromise their immune systems. Previous research had suggested that some individuals experienced relapses post-vaccination, which deterred others from getting recommended booster shots. However, Moisset’s team found no increased risk of relapse for the majority of participants following vaccination.
The study assessed relapse risks specifically after booster doses among patients with high MS activity, defined as those with at least two relapses in the preceding two years, particularly among those who were not undergoing any MS treatment.
The research involved 124,545 MS patients in France, who had been living with the condition for an average of 14 years, and they were monitored for 45 days post-vaccination, acknowledging that vaccine-induced relapses typically occur within 28 days. Among the participants, 82% received at least one dose of a COVID-19 vaccine, with 95% receiving a second dose and 59% obtaining an additional booster. Vaccines included Pfizer BioNTech, Moderna, AstraZeneca, or Janssen.
During the follow-up period, researchers focused on relapses necessitating treatment with high-dose corticosteroids. After accounting for various influencing factors—such as seasonality and the effects of disease-modifying therapies—results indicated that COVID-19 vaccination did not elevate the risk of severe relapses, and this was consistent across all vaccine doses.
To further validate their findings, they compared relapse cases with those who did not experience relapses and again found no correlation with vaccine exposure, noting a slight decrease in relapse risk post-vaccination.
Moisset expressed that the findings are reassuring, emphasizing that the vaccines can be safely administered without concerns of relapse, which is particularly important for patients who may need booster shots in the future. However, he noted that extra caution is advised for patients exhibiting the highest inflammatory activity; these patients should be treated with disease-modifying therapies prior to receiving booster vaccinations. The increased risk after the third dose was notably higher in individuals who were untreated or had highly active MS.
One limitation identified was that the study only encompassed relapses requiring corticosteroid treatment, thus omitting milder relapses that may not have warranted intervention from neurologists.