COVID-19 Vaccination Does Not Increase Risk for Relapse in Patients With MS

Most patients with multiple sclerosis (MS) do not experience a significant increase in relapse risk requiring corticosteroid therapy after receiving the COVID-19 vaccination, according to study results published in Neurology.

Researchers conducted a nationwide cohort study sourcing data from the French National Health Data System between January 2009 and March 2022 to gauge the risk for severe relapse within 45 days of receiving 1, 2, or 3 (booster) doses of COVID-19 vaccination among patients with MS. Patients with MS who had a long-term disease code for MS, were hospitalized for MS, or received MS-specific disease-modifying therapies were eligible for inclusion. The primary outcome was treated MS relapse. Secondary outcomes were relapse rates across various subgroups categorized by vaccine type and patient characteristics. Researchers also assessed patient demographics and comorbidities, DMT status, and disease duration. The potential risk for relapse associated with COVID-19 vaccination was evaluated using 2 self-controlled designs: the self-controlled case series method, which is well-suited to studying adverse reactions to vaccines, and the case-time control method. Poisson regression models and logistic regression were used in statistical analyses.

A total of 124,545 patients with MS were identified for inclusion, of whom 102,524 (82.3%; mean age, 54.3; women, 71.8%) received at least 1 dose of COVID-19 vaccine and 22,021 (17.7%; mean age, 52.6; women, 70.5%) were not vaccinated against COVID-19.

A total of 259,880 doses were administered. Second doses were received by 96,990 (94.6%) of those who received a first dose and 60,366 (58.9%) received a booster dose.  

There was no observed increase in relapse risk following the first (incidence rate ratio [IRR], 1.01; 95% CI, 0.88-1.15; P =.93), second (IRR, 1.02; 95% CI, 0.94-1.12; P =.61), or booster (IRR, 1.00; 95% CI, 0.90-1.11; P =.79) doses. Excluding the pre-exposure periods, the combined IRR for all 3 doses was 0.97 (95% CI, 0.91-1.03; P =.30). A slight excess risk for relapse was found following the booster dose among patients not receiving any disease-modifying therapy.

Among patients who had had at least 2 relapses in the prior 2 years, an increased risk for relapse following the booster dose was observed (IRR, 1.28; 95% CI, 1.07-1.53; P =.006).

There was no excess risk for relapse associated with either of the 2 mRNA (BNT162b2 and mRNA-1273) or viral vector (ChAd)xl nCoV-19 and Ad26.COV2) vaccines.

The case-time control study confirmed the self-controlled case series findings, indicating no increased relapse risk following any of the 3 vaccination doses, even noting a minor decrease in the risk for relapse (odds ratio, 0.90; 95% CI, 0.83-0.98; P =.01).

Study limitations include the possible underestimation of the annualized relapse rate and misclassification of hospitalizations.

“These findings are reassuring and have direct implications for the management of patients with MS in the context of pandemics,” the study authors concluded.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.