A new study suggests there is no link between overall exposure to the diphtheria, tetanus, poliomyelitis, pertussis, and Haemophilus influenzae, influenza, and pneumococcal vaccines, and multiple sclerosis flare-ups requiring hospitalization.

Scientific literature is sparse when it comes to the association of vaccination with the onset of MS flare-ups. Immunization by vaccines of the entire population is crucially important for public health. A nationwide study of the French population sought to evaluate the risk of hospitalization for severe MS flare-ups after vaccination in patients with MS.

This cohort study included patients diagnosed with MS between Jan. 1, 2007, and Dec. 31, 2017, who were included in the System of National Health Databases, a national health claims database in France. Cases were defined by vaccine exposure prior to the onset of hospitalization because of an MS flare-up, and flare-up rates were compared with those that occurred prior to vaccine exposure in up to four control time windows immediately preceding the at-risk time window (i.e., the MS flare-up) for each patient. Data were analyzed from January 2022 to December 2022. Receipt of at least one vaccination, including the diphtheria, tetanus, poliomyelitis, pertussis, or Haemophilus influenzae vaccine, influenza vaccine, and pneumococcal vaccine, during follow-up.

Among 35,265 patients with MS who had a flare-up requiring hospitalization and received at least one vaccine, including the diphtheria, tetanus, poliomyelitis, pertussis, and Haemophilus influenzae vaccine, the influenza vaccine, or the pneumococcal vaccine, no link was found with severe MS flare-ups and vaccine exposure in the 60 days prior to the flare-ups.

However, the researchers noted that considering the number of vaccine subtypes available, further studies are needed to confirm these results.

The findings were published in JAMA Neurology.