Adverse Events Following Immunization Among Children With Epilepsy: A Self-Controlled Case Series

Area of Science:

• Pediatrics
• Neurology
• Immunology

Background:

• Fever and illness can trigger seizures in children with epilepsy.
• Concerns exist that vaccine-induced inflammation and fever might also trigger seizures.
• This study investigated the risk of seizures following immunization in children with epilepsy.

Purpose of the Study:

• To estimate the risk of emergency department (ED) visits or hospitalizations for epilepsy/seizure after immunization in children younger than 7 years with epilepsy.
• To assess the risk of all-cause ED visits or hospitalizations post-immunization in this population.

Main Methods:

• A self-controlled case series design was used, analyzing administrative healthcare data from Ontario and Manitoba, Canada (2005-2015).
• Children diagnosed with epilepsy before age 7 and immunized were included.
• Age- and season-adjusted relative incidence (aRI) of ED visits/hospitalizations was calculated for specific periods post-inactivated and live immunizations compared to a control period.

Main Results:

• The risk of epilepsy/seizure-related ED visits/hospitalizations modestly increased 0-2 days after inactivated vaccines (aRI = 1.5) and 7-10 days after live vaccines (aRI = 1.9).
• All-cause ED visits/hospitalizations showed a combined aRI of 0.9 after inactivated vaccines and 1.3 after live vaccines during the respective risk periods.
• These findings indicate a slight increase in seizure risk following vaccination in children with epilepsy.

Conclusions:

• The risk of epilepsy/seizure-related ED visits/hospitalizations is modestly increased in children with epilepsy following inactivated and live vaccines.
• This increased risk occurs during periods of peak fever and inflammation post-vaccination.
• These risks should be weighed against the significant benefits of protection from vaccine-preventable diseases.