Individuals diagnosed with multiple sclerosis (MS) often express concern about potential symptom intensification or recurrence following vaccination with live attenuated vaccines, leading to hesitancy. However, a recent investigation published in JAMA Network Open suggests that MS patients can safely receive live attenuated vaccines, specifically the measles, mumps, and rubella (MMR) and chickenpox (varicella) vaccines, without an elevated risk of symptom relapse.
The study’s authors concluded, "The results support the administration of these vaccines when indicated and may help reassure clinicians and patients, reducing vaccine hesitancy."
Live attenuated vaccines function by introducing a weakened, yet still viable, version of a virus. This stimulates a strong immune response, equipping the recipient to fend off the targeted diseases.
No Increased Relapses Observed in Vaccinated MS Patients
A retrospective cohort study, spearheaded by researchers at the University of Vic–Central University of Catalonia in Spain, examined 369 adult MS patients. Within this cohort, 123 individuals received at least one dose of the live attenuated chickenpox vaccine and/or MMR vaccine between July 2016 and October 2024. The remaining 246 individuals did not receive these vaccines during the study period.
"The results support the administration of these vaccines when indicated and may help reassure clinicians and patients, reducing vaccine hesitancy."
The researchers recorded a total of 36 relapses. Of these, 15 occurred in vaccinated individuals (41.7%), while 21 occurred in unvaccinated controls (58.3%). The findings indicated that vaccination did not lead to an increase in symptom relapses compared to the control group.
For the purpose of this study, a relapse was defined as the emergence of new neurological signs or the worsening of existing symptoms that persisted for a day or more post-vaccination, in the absence of fever or infection. Crucially, any documented relapse had to occur at least 30 days after a prior relapse.
The authors highlighted that vaccine uptake remains relatively low among MS patients. This is attributed to concerns held by some patients and healthcare providers that live attenuated vaccines might provoke new symptoms or exacerbate pre-existing ones. The researchers expressed hope that these findings will alleviate the concerns of MS patients regarding the safety of live attenuated vaccines, particularly in light of recent measles outbreaks in both the United States and Europe.
They emphasized, "Demonstrating the safety of MMR vaccination, even in a population traditionally perceived as vulnerable, such as people with MS, is therefore highly relevant for both clinical practice and public health policy."