A Vall d’Hebron study confirms the safety of live attenuated vaccines in people with multiple sclerosis

In the context of World Multiple Sclerosis Day, celebrated on 30 May, a study jointly led by the Centre for Multiple Sclerosis of Catalonia (Cemcat) and the Preventive Medicine Service of Vall d’Hebron reinforces the safety of live attenuated vaccines in people with multiple sclerosis (MS).

The work, published in JAMA Network Open, concludes that vaccines against measles, rubella, mumps (MMR) and varicella are not associated with an increased risk of relapses or inflammatory activity of the disease.

The study analyzes data from 369 people with MS followed at Cemcat between 2016 and 2024. Of these, 123 received at least one dose of a live attenuated vaccine because they had no demonstrated prior immunity to measles or varicella. Researchers compare the evolution of the 123 vaccinated patients with that of 246 unvaccinated people with MS and observe that the risk of relapse during the year after vaccination is not higher than that of controls. In addition, available MRI analyses also show no increase in inflammatory activity after vaccination.

“This study provides much-needed evidence in a context where doubts still exist about the safety of these vaccines in people with multiple sclerosis,” explains Dr. René Carvajal, researcher in the Clinical Neuroimmunology group at Vall d’Hebron Institut de Recerca (VHIR) and neurologist at Cemcat. “The results indicate that these vaccines can be safely administered when indicated, especially before starting immunosuppressive treatments.”

Live attenuated vaccines play a particularly important role before starting some high-efficacy treatments for MS that may have immunosuppressive effects. These drugs may increase the risk of serious complications from infections such as measles or varicella. In this context, ensuring appropriate vaccination is an important part of therapeutic planning.

Dr. Mar Tintoré, clinical head of the Neurology/Neuroimmunology Service at Vall d’Hebron, principal investigator of the Clinical Neuroimmunology group at VHIR and clinical head of Cemcat, emphasizes that “vaccine hesitancy remains frequent among people with MS, often due to fear that vaccination could trigger disease relapses.” In Vall d’Hebron, from Cemcat, continues Dr. Tintoré, “our concern has remained for years due to the lack of specific studies on live attenuated vaccines in this population.”

“The data are especially relevant now that measles cases have increased in different countries and vaccination coverage has decreased in some settings,” says Dr. Susana Otero-Romero, assistant physician in the Preventive Medicine Service of Vall d’Hebron University Hospital, head of the Epidemiology and Public Health group at VHIR and researcher at Cemcat. “Having solid scientific evidence allows us to transmit more confidence both to patients and to healthcare professionals.”

The results may also help speed up access to disease-modifying treatments. Many people with MS need to complete vaccination before starting immunosuppressive therapies, as these vaccines may be contraindicated once treatment has begun.

The importance of medical counselling in the face of misinformation

In parallel, a study carried out by Vall d’Hebron and published in Patient Education and Counseling has analyzed the impact of misinformation on reproductive decisions of women with multiple sclerosis. The work, also led by researchers from Cemcat and VHIR, shows that many misconceptions about pregnancy and motherhood in the context of the disease still persist.

The study includes 200 women aged 18 to 45 and reveals that 59% consider that MS has influenced their decisions regarding motherhood, mainly by modifying the timing of pregnancy or the number of desired children. Among the most common concerns are the risk of worsening after childbirth, the possibility that children may develop MS, or the effects of treatments on the fetus.
Researchers also detect important gaps in information about aspects such as breastfeeding, the use of certain treatments during pregnancy, or the real risks of disease transmission. Even so, only one in four participants had recently received counseling about pregnancy and MS.

“Accurate and individualized health information is key for people with multiple sclerosis to make informed decisions about their health and life project,” explains Dr. Miguel Ángel Robles, principal investigator of the multidisciplinary nursing research group at VHIR and nursing coordinator at Cemcat.