- Seizures were more common in immunized vs nonimmunized children with epilepsy, but immunized children did not have significantly elevated risk in first postimmunization days and weeks compared with the latter.
Why this matters
- Vaccines have been associated with febrile seizures but not afebrile seizures in young children.
- Risk in children with preexisting epilepsy is unclear.
- 80 children had immunization visits, 67 had no immunization visits, 155 had no available immunization records.
- Mean number of seizures was 2.5, 0.7, 0.9, respectively (P<.001).
- Among immunized children, with 21-83 days postimmunization as control period, risk for medically attended seizure was not significantly increased during 0-14 days after any vaccine (relative risk [RR], 1.14; 95% CI, 0.46-2.83).
- Findings similar for 0-2 days after receipt of inactivated vaccines (RR, 0.95; 95% CI, 0.13-7.06).
- Risk after live vaccines not calculable because of too few events.
- Upper limit of attributable risk was just 1 seizure/25 immunizations during 0-14 days and 1 seizure/75 inactivated immunizations during 0-2 days.
- Canadian retrospective cohort study of 302 children <7 years of age with epilepsy during 2010-2014.
- Main outcome: seizure risk.
- Funding: IWK Health Center, Canada.
- Small sample size.
- Missing/incomplete records.
- Some seizures not captured.