No Additional Short-Term Risk of MS Relapse After COVID Vaccine

Short-term risk of multiple sclerosis (MS) relapse did not rise after COVID-19 vaccination, a preliminary analysis in Italy showed.

Among 324 MS patients who received the Pfizer-BioNTech COVID-19 mRNA vaccine (Comirnaty), six clinical relapses occurred in the 2 months before vaccination (1.9%) and seven occurred in the 2 months after vaccination (2.2%), reported Massimiliano Di Filippo, MD, of the University of Perugia, and co-authors in the Journal of Neurology, Neurosurgery, and Psychiatry.

The incidence of relapses 2 months before and after vaccination was not statistically different (B 0.154, 95% CI -0.948 to 1.288, P=0.78).

Vaccine safety in people with MS has been a matter of debate, Di Filippo and colleagues noted. “In the current COVID-19 pandemic scenario, the availability of mRNA vaccines warrants the urgent need to define their safety in people with MS.”

The analysis represents the first prospective study of a large cohort of MS patients followed for at least 2 months after the first dose of the Pfizer vaccine, the researchers said.

The study included patients from 25 Italian MS tertiary centers who had a first dose of the Pfizer vaccine in January 2021. Database lock was on March 31.

Of the 324 MS patients in the study, 322 had both doses of the Pfizer vaccine, spaced 21.5 days apart. Twenty-eight people (8.6%) had experienced SARS-CoV-2 infection confirmed by a molecular swab, 225 days before their first vaccine dose.

Most people in the study (74.7%) were female, and mean age was about 43. Most patients (93.5%) had relapsing-remitting MS; 4.6% had secondary progressive and 1.9% had primary progressive disease. Mean disease duration was 11.9 years, and mean Expanded Disability Status Scale (EDSS) score at the time of vaccination was 2.1, indicating minimal disability.

The mean time between the first vaccine and clinical relapse was 44 days. Age, sex, disease duration, or EDSS score had no effect on relapse occurrence. Five relapses were monofocal and two were multifocal. At the time of vaccination, three patients were treated with dimethyl fumarate (Tecfidera), one with glatiramer acetate (Copaxone), two with ocrelizumab (Ocrevus), and one was not treated.

The findings reiterate those seen in Israel, where researchers reported a similar rate of acute relapse in 555 MS patients after Pfizer COVID-19 vaccination. In the Israel study, however, the follow-up period was variable: about 20% of patients with relapses were followed for less than 14 days after immunization, Di Filippo and co-authors observed.

Limitations of the current study, the team said, include its lack of MRI data and the only 2 months of follow-up. In addition, since only 6.5% of patients had progressive MS, no clear conclusions can be drawn about that group, the researchers added.

“Larger observational studies with longer follow-up would be desirable,” the investigators wrote. “Despite these limitations, we think that the results of our study can improve clinical practice driving clinical decisions and support the recommendation to promote access of people with MS to COVID-19 vaccination.”