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Health experts recommend that people with multiple sclerosis get fully vaccinated. Luis Velasco/Stocksy
  • Researchers say vaccines do not appear to raise the risk of multiple sclerosis (MS) flare-ups requiring hospitalization.
  • They say the findings may help dispel some concerns about vaccines causing the development of MS or flare-up incidents.
  • The American Academy of Neurology advises people with MS to get fully vaccinated.

Vaccines don’t appear to trigger major flare-ups of multiple sclerosis (MS, a new study published in the journal JAMA Neurology concludes.

In their work, researchers studied the medical records of more than 100,000 people in a national health claims database in France.

The study looked at reports of vaccine exposure prior to the onset of hospitalization due to an MS flare-up, then compared these flare-up rates with those that occurred prior to vaccine exposure for each person.

Vaccines examined in the study included diphtheria, tetanus, poliomyelitis, pertussis (Haemophilus influenzae), influenza, and pneumococcal. The COVID-19 vaccine was not included because the study period occurred prior to the start of the 2020 pandemic.

Of the 106,523 people with MS in the study, about a third experienced a flare-up of symptoms requiring hospitalization during the study period.

The researchers reported there was no significant association between the flare-ups and exposure to any of the vaccines studied.

“However, considering the number of vaccine subtypes available, further studies are needed to confirm these results,” the study authors wrote.

“Many relapses in the U.S. are treated on an outpatient basis, so a patient might be more reassured by a study that looked at the association between relapses and vaccination,” Julie Fiol, a multiple sclerosis certified nurse and associate vice president for clinical innovation and strategy at the National MS Society, told Medical News Today.

“In general, studies have concluded vaccination is safe for people living with MS.”

Fiol said that vaccines “are a key strategy for preventing illness and are especially crucial for people with chronic health conditions and those using immunocompromising medications.”

“For years many have believed vaccines trigger MS relapses, and there is much misinformation available online and on social media currently to support this false claim,” she said.

“Studies are needed to dispel these myths and to help people make informed decisions about their health with their healthcare professional.”

Multiple sclerosis is the most common chronic inflammatory demyelinating disease of the central nervous system, affecting more than 2.8 million people worldwide.

Demyelination is the process where the protective covering (myelin sheath) of the nerve fibers in the central nervous system is damaged, disrupting the efficient flow of signals between the brain and the body.

The underlying causes of MS remain unknown, however.

Some studies have found that systemic infections, even those suppressed by vaccines, can trigger flare-ups of MS symptoms.

“Research has shown us that infections can trigger MS relapses and that vaccination is safe,” said Fiol.

Fiol also emphasized the safety of vaccination, stating that other studies have demonstrated that the COVID-19 vaccines are safe for people with MS.

“Although the evidence remains inconclusive, this debate has spurred doubts and potentially detrimental vaccination hesitancy, highlighting the need for well-conducted large-scale studies to examine the association,” wrote Lamiae Grimaldi, PhD, PharmD, a study lead author and an assistant professor in the Department of Development Biology at the Paris-based Pasteur Institute and colleagues.

“While several studies have been conducted on the association between vaccination and MS onset, evidence on the association of vaccination with disease activity (flare-ups) and progression among patients with MS remain scarce.”

— Lamiae Grimaldi, PhD, PharmD, lead study author

The American Academy of Neurology recommends that people with MS receive recommended vaccinations, including yearly flu shots.

The guidelines, issued in 2019, note that while evidence at that time was inconclusive about whether MS flare-ups could be triggered by vaccines, people with MS were advised to delay getting vaccines until any active flare-up of symptoms subsided.

In 2021, a study published in the journal Nature Medicine concluded that the COVID-19 vaccine could help people with MS produce antibodies to fight the novel coronavirus, even if they received anti-CD20 treatment that inhibits a class of antibodies believed to contribute to MS attacks.

A recently developed vaccine against the Epstein-Barr virus also may help prevent MS, according to a study published earlier this year in the journal Nature Communications.

In 2022, a study published in the journal Science estimated that infection with the Epstein-Barr virus increased the risk of developing MS 32-fold.