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The Omicron variant of SARS-CoV-2 is more likely to cause febrile seizures and unconsciousness in children than non-Omicron variants

Febrile seizures or convulsions occur in young children. The majority of febrile seizures occur in children between 12 and 18 months of age. They are triggered by a fever above 38.3 degrees Celsius (101 degrees Fahrenheit). Febrile seizures can occur due to the fever accompanying bacterial or viral infections or as a side effect of certain vaccines. The authors from Japan conducted this study to determine how variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) influence the occurrence of simple or complex febrile seizures in infected children.

About the study

The study included 557 children infected with the Omicron variant of SARS-CoV-2 and 214 children infected with the non-Omicron variants of SARS-CoV-2. Children aged 0–15 years were diagnosed with coronavirus disease (COVID-19) by reverse transcription polymerase chain reaction for SARS-CoV-2 or antigen test and were hospitalized for COVID-19 from January 2020 to October 2022. The children in the Omicron group were significantly younger, with a mean age of 5.3 ± 4.4 years, whereas in the non-Omicron group, the mean age was 6.1 ± 4.7 years.

The data from the medical records included age, date of arrival at the hospital, gender, and various neurological and clinical symptoms, such as seizures and disorders of consciousness. The seizures were categorized as follows: 1. the seizure that occurred once and stopped within five minutes was categorized as a simple febrile seizure, 2. the seizure that occurred more than twice within 24 hours was categorized as a complex seizure, and 3. prolonged seizure was categorized as status epilepticus.

Simple and complex febrile seizures occurred with significantly different rates in the two groups. One of 133 febrile participants in the non-Omicron group, and 92 of 534 febrile participants in the Omicron group, had a simple or complex febrile seizure. In the group of 92 children diagnosed with the Omicron variant who experienced febrile seizures, 49%  had simple febrile seizures, 25% complex febrile seizures, 11% status epilepticus, and 2% encephalopathy.


This study has shown that the Omicron variant of SARS-CoV-2 is more likely to cause seizures and unconsciousness in pediatric patients compared to the non-Omicron variants. The authors emphasized a need for further research involving more institutions and larger sample sizes.

This study was published in Frontiers in Pediatrics.

Journal Reference

Tokuyama K, Kitamura T, Maruyama K, et al. High number of seizures and unconsciousness in patients with SARSCoV-2 Omicron variants: a retrospective study. Front. Pediatr. 2023; 11:1273464. (Open Access).


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