Epidemiology and Health

Won-Chul Shin

1 Article

Risk of new-onset seizures following immunization against COVID-19: a self-controlled case-series study: Hwa Yeon Ko, Dongwon Yoon, Ju Hwan Kim, Han Eol Jeong, Seung Bong Hong, Won-Chul Shin, Ju-Young Shin, on behalf of the CoVaSC Investigators; Epidemiol Health. 2025;47:e2025024. Published online May 2, 2025; DOI: https://doi.org/10.4178/epih.e2025024

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
Despite emerging reports of new-onset seizures (NOS) following coronavirus disease 2019 (COVID-19) vaccination, safety evidence regarding the risk of NOS after vaccination remains limited. We aimed to investigate the potential association between NOS and COVID-19 vaccination.
METHODS
We conducted a self-controlled case series study utilizing a nationwide database linking the COVID-19 vaccination registry and the National Health Information Database (from February 2021 to October 2022). We identified adults (≥18 years) who received COVID-19 vaccination (BNT162b2, ChAdOx1 nCoV-19, mRNA-1273, NVX-CoV2373, or Ad26.COV2.S) and had a diagnosis of NOS accompanied by prescriptions of anti-seizure drugs. The observation period was defined as 240 days following vaccination. We evaluated the risk of NOS during a risk window of 28 days after vaccination compared to the control window (the remaining observation period excluding the risk window). Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were estimated using a conditional Poisson regression model.
RESULTS
Among 42,155,198 COVID-19 vaccine recipients, we identified 1,849 and 4,217 patients with NOS in the risk and control windows, respectively. There was no increased risk of NOS within the 28-day period following vaccination (IRR, 0.99; 95% CI, 0.94 to 1.05). Although results from subgroup analyses by vaccine type were largely consistent with the main findings (IRR, 0.95; 95% CI, 0.88 to 1.03 for BNT162b2; IRR, 0.95; 95% CI, 0.77 to 1.16 for ChAdOx1 nCoV-19; IRR, 1.58; 95% CI, 0.52 to 4.83 for Ad26.COV2.S), a marginally elevated risk was observed for mRNA-1273 (IRR, 1.21; 95% CI, 1.04 to 1.42).
CONCLUSIONS
There was no evidence of an increased risk of NOS following COVID-19 vaccination. These findings can be used as safety evidence in clinical decision-making and to bolster public confidence in COVID-19 vaccines.; Summary

Korean summary
· 질병관리청 코로나19백신 접종 등록자료와 국민건강보험공단의 청구 데이터베이스 연계 자료원을 활용하여 코로나19백신 접종과 경련/발작 발생 간의 관련성에 대한 안전성 평가를 수행함. · 자기-대조환자군 연구설계를 적용하여 4,215만 명 이상의 코로나19백신 접종자를 대상으로 분석한 결과, 대부분의 백신 종류에서 접종 후 28일 이내에 경련/발작 발생 위험이 증가하지 않았으며, mRNA-1273 백신에서만 위험이 다소 증가한 것으로 나타남. · 전반적으로, 본 연구는 코로나19백신 접종 후 경련/발작 발생 위험이 증가하지 않음을 보여주었으며, 이는 임상적 의사결정과 백신 안전성에 대한 신뢰를 높이는 근거로 활용될 수 있음.

Key Message
· A nationwide self-controlled case series study investigated whether COVID-19 vaccination increases the risk of new-onset seizures (NOS) in adults by analyzing over 42 million vaccine recipients. · The results showed no increased risk of NOS within 28 days after vaccination for most vaccine types, with the exception of a marginally elevated risk for the mRNA-1273 vaccine. · Overall, the study found no evidence of increased NOS risk following COVID-19 vaccination, supporting the safety of these vaccines for clinical decision-making.

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