PATIENTS with MS receiving live attenuated vaccination did not experience increased relapse activity compared with unvaccinated controls, according to a new cohort study that could reduce hesitancy surrounding MMR vaccine use in people living with MS.
Vaccination Guidance for People With MS
Live attenuated measles-mumps-rubella and varicella vaccines are recommended for immunocompetent individuals with MS who lack immunity, particularly before starting immunosuppressive therapy. However, concerns regarding relapse activity after vaccination have contributed to hesitancy among patients and clinicians. Researchers therefore investigated whether MMR vaccine administration in people with MS was associated with increased relapse risk within one year of vaccination.
Matched Cohort Analysis in Barcelona
This cohort study analysed prospectively collected data from July 2016 to October 2024 at a tertiary MS centre in Barcelona, Spain. Investigators included 369 people with MS, comprising 123 vaccinated participants matched 1:2 with 246 unvaccinated controls according to sex, age, and timing of first demyelinating event. Vaccinated individuals received at least one dose of live attenuated MMR or varicella vaccine due to serologic susceptibility. Mean age was 28.75±8.72 years among vaccinated participants and 28.66±8.60 years among controls, while 69.1% of both groups were female.
Relapse Activity Was Not Increased
Researchers observed 36 relapse events overall, including 15 events (41.7%) among vaccinated participants and 21 events (58.3%) among unvaccinated controls. Weighted Poisson analysis showed no significant difference in relapse incidence between groups, with an incidence rate ratio of 0.52 (95% CI, 0.23–1.06). Weighted Cox regression similarly found no increase in relapse hazard after vaccination (HR 0.55; 95% CI, 0.25–1.17). Sensitivity analyses adjusting for postbaseline treatment exposure produced similar findings (HR 0.60; 95% CI, 0.27–1.33).
Implications for Clinical Practice
The authors concluded that live attenuated vaccination was not associated with increased relapse risk in nonimmunosuppressed people with MS. These findings support current recommendations for MMR vaccine use in patients with MS before initiating high-efficacy disease-modifying therapy and may help clinicians address persistent vaccine hesitancy.
Reference
Carvajal R et al. Live attenuated measles-mumps-rubella and varicella vaccinations and multiple sclerosis activity. JAMA Netw Open. 2026;9(5):e2613742.
Featured image: Leigh Prather on Adobe Stock
