Risk of MS Relapse Not Increased by COVID-19 Vaccine, Study Finds

Marisa Wexler MS avatar

by Marisa Wexler MS |

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Getting the Pfizer-BioNTech vaccine for COVID-19 does not increase the risk of multiple sclerosis (MS) relapses in the two months following vaccination, according to a new study.

The results support recommending COVID-19 vaccines for people with MS, its researchers said.

“The incidence of relapses in the 2 months before and after vaccination was not statistically different,” the investigators wrote.

The study, “mRNA COVID-19 vaccines do not increase the short-term risk of clinical relapses in multiple sclerosis,” was published in the Journal of Neurology, Neurosurgery and Psychiatry.

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COVID-19 Vaccine Trial Testing Extra Dose in MS, Other Diseases

The BNT162b2 vaccine is a messenger RNA (mRNA)-based vaccine for COVID-19. In simple terms, it works by delivering the instructions to make a piece of the SARS-CoV-2 virus — which causes COVID-19 — to the body’s cells. The cells can then make this viral piece, and the immune system “learns” to recognize this piece of virus and defend the body against it.

In clinical trials, it has been well-established that this and other COVID-19 vaccines are generally safe and can significantly reduce the risk of severe disease or death from COVID-19. However, because vaccines work by activating the immune system — and the over-activity of the immune system is what causes autoimmune diseases like MS — there has been some concern over potential safety risks of the COVID-19 vaccine in people with such diseases.

Now, researchers in Italy reported on data for 324 MS patients who were given the Pfizer-BioNTech vaccine earlier this year, and were followed for at least two months.

“Our study is the first prospective study including a large cohort of patients with MS who were followed, with a self-controlled design, for at least 2 months after the first dose of the Pfizer-BioNTech BNT162b2 vaccine,” the researchers wrote.

Among the vaccinated patients, 28 (8.6%) had previously tested positive for SARS-CoV-2 infection. About three-quarters of the patients were female, the average age was about 43, and 93.5% had relapsing-remitting MS.

All but two of the patients received both doses of the vaccine according to the normal schedule, which is about three weeks apart. One patient did not receive a second dose because the individual tested positive for SARS-CoV-2 infection after the first dose, and another delayed the second dose because a pre-scheduled MRI scan performed after the first dose revealed a possible increase in brain inflammation.

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In the two months prior to receiving the vaccination, six MS relapses were reported in six of the patients. In the two months after the vaccination, seven patients reported seven clinical relapses.

Statistical analyses demonstrated that the rate of relapse before and after the vaccination was not significantly different. No demographic or clinical characteristics showed a significant association with relapse risk in additional analyses.

A limitation of the study is that regular MRI scans were not done, so it’s possible some patients may have had brain inflammation that did not cause overt symptoms, according to the scientists. Another noted limitation is the low proportion of participants with progressive types of MS.

“Larger observational studies with longer follow-up would be desirable,” the researchers 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,” the team concluded.

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