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Risk of seizures after measles-mumps-rubella immunization
M R Griffin1, W A Ray, E A Mortimer
1Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2637.
Insights
Measles-mumps-rubella (MMR) and measles-rubella (MR) immunizations were evaluated for seizure risks in children. A slight, though not statistically significant, increase in febrile seizures occurred within 7–14 days post-MMR/MR vaccination.
Area of Science:
- Pediatric Neurology
- Immunology
- Public Health
Background:
- Measles-mumps-rubella (MMR) and measles-rubella (MR) vaccines are crucial for childhood disease prevention.
- Concerns exist regarding potential neurologic adverse events, specifically seizures, following vaccination.
Purpose of the Study:
- To assess the risk of seizures and other neurologic events after MMR or MR immunization in young children.
- To determine if there is a temporal association between vaccination and seizure occurrence.
Main Methods:
- A retrospective cohort study design was employed.
- 18,364 children in Tennessee enrolled in Medicaid, vaccinated within their first 3 years of life, were analyzed.
- Seizure and encephalopathy events were tracked from immunization up to 36 months of age.
Main Results:
- No encephalopathies were observed during the study period.
- One hundred children experienced seizures between immunization and 36 months.
- A relative risk of 2.1 (95% CI: 0.7 to 6.4) for febrile seizures was noted in the 7–14 days post-immunization interval compared to later intervals, though this was not statistically significant.
Conclusions:
- The study found no statistically significant increase in seizures or encephalopathy following MMR/MR immunization.
- The observed slight increase in febrile seizures shortly after vaccination aligns with known fever responses to vaccines and is consistent with prior research.
- MMR and MR immunizations appear safe regarding major neurologic events like seizures in the studied population.
Abstract:
To evaluate the risks of seizures and other neurologic events following measles-mumps-rubella (MMR) or measles-rubella (MR) immunization, a retrospective cohort study was conducted among 18,364 Tennessee children enrolled in Medicaid who received MMR or MR immunizations in their first 3 years of life. One hundred children had seizures at some time between immunization and 36 months; there were no encephalopathies during this period. Four children had febrile seizures in the 7 through 14 days following MMR or MR immunization compared with 72 in the interval 30 or more days following MMR or MR immunization yielding a relative risk (95% confidence interval) of 2.1 (0.7 to 6.4). Although not statistically significant, this increase in febrile seizures in the 7- through 14-day interval following MMR immunization is coincident with the occurrence of fever following MMR immunization and is consistent with reports of other investigators.