Loading ...

Live attenuated measles-mumps-rubella (MMR) and varicella vaccines were not associated with an increased risk of relapse in immunocompetent patients with multiple sclerosis (MS).

In a large cohort study, vaccinated patients did not experience higher relapse rates or greater MRI activity than matched unvaccinated peers — findings that may help reassure clinicians counseling patients about vaccination before initiation of immunosuppressive disease-modifying therapies (DMTs), researchers said.

“The results support the administration of these vaccines when indicated and may help reassure clinicians and patients, reducing vaccine hesitancy,” wrote the investigators led by René Carvajal, MD, of the Multiple Sclerosis Centre of Catalonia in Barcelona, Spain.

The study was published online May 20 in JAMA Network Open. 

Reassuring Results

Live attenuated MMR and varicella vaccines are recommended for immunocompetent patients with MS lacking immunity, particularly before starting high-efficacy immunosuppressive therapies that increase vulnerability to vaccine-preventable infections. 

Rising global measles incidence has heightened the urgency of ensuring adequate immunity before immunosuppressive treatment.

However, concerns about postvaccination relapse may contribute to vaccine hesitancy among both patients and clinicians, and “robust data addressing this risk remain limited,” the researchers noted. 

To evaluate safety, they conducted a retrospective cohort study using prospectively collected data for 123 adults with MS who received at least one dose of live attenuated MMR and/or varicella vaccine due to documented serologic susceptibility. 

Vaccinated patients were matched (1:2) to 246 unvaccinated controls based on age, sex, and timing of first demyelinating event. 

The mean age in both groups was roughly 29 years, and about 69% were women. Most vaccinated patients received the MMR vaccine (76%), while 21% received varicella vaccine and 3% received both.

Overall, 36 relapses occurred during the 12 months following vaccination — 15 among vaccinated and 21 among unvaccinated patients. In weighted analyses, the incidence of relapse was not significantly higher in the vaccinated group (incidence rate ratio, 0.52). 

Similarly, Cox proportional hazards regression models showed no significant difference in risk of relapse between groups (HR, 0.55). Both analyses met the study’s predefined noninferiority threshold, indicating that vaccination did not result in a clinically unacceptable increase in relapse risk.

The results were similar in sensitivity analyses adjusting for DMT exposure after baseline, as well as in analyses limited to the first 3 months after vaccination — the period considered at highest risk for vaccine-related inflammatory activity. 

Notably, no postvaccination relapses or vaccine-strain infections occurred among the four patients receiving natalizumab who required urgent vaccination before further therapy escalation of active disease. 

Researchers also performed an exploratory MRI-based case-crossover analysis in 50 vaccinated patients who had imaging available before and after vaccination. Rather than showing increased inflammatory activity after vaccination, MRI or relapse events were lower in the postvaccination period than in the prevaccination period (21 vs 43 events; P < .001).

Limitations of the study include its observational design, relatively small number of relapse events, and inability to separately analyze MMR and varicella vaccines due to limited statistical power. MRI surveillance was also not standardized across all participants. 

“Future larger studies may help clarify safety according to vaccine type, dose schedule, and concurrent DMT exposure, particularly in patients receiving high-efficacy therapies,” the authors noted. 

For now, the findings “support administration of live attenuated MMR and varicella vaccines in patients with MS and current recommendations for appropriate immunization before immunosuppressive therapy and may lead to reduced vaccine hesitancy,” they concluded. 

The study had no commercial funding. Disclosures for the authors are available with the original published article.