Impact of the Omicron strain on febrile convulsions in children: A single-center observational study

The emergence of the Omicron strain of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the end of December 2021 has drastically increased the number of infected children in Japan, along with the number of children with febrile convulsions. However, impact of the Omicron strain on the febrile convulsions in children is not clear. We compared the frequency of SARS-CoV-2 infection in children hospitalized with febrile convulsions with the frequency of SARS-CoV-2 infection in children with fever and respiratory symptoms without convulsions. In 2021 and 2022, 49 and 58 children, respectively, required emergency hospitalization for febrile convulsions (FC group), in which 24 and 38 children underwent a Filmarray respiratory panel ® test (FA test) and quantitative antigen test for SARS-CoV-2, respectively. In 2022, only six patients tested positive for SARS-CoV-2 (10.3%, 6/58). As a reference group, 655 children aged < 10 years who underwent the FA test for fever and respiratory symptoms during the same period were investigated, and 4 (1.8%, 4/223) and 42 (9.7%, 42/432) tested positive for SARS-CoV-2 in 2021 and 2022, respectively. Rhinovirus/enterovirus (RV/EV) was the most frequently detected virus, followed by respiratory syncytial virus (RSV) and parainfluenza virus 3 (PI3); no significant difference in the trend of detected viruses was observed between the two groups. The frequency of febrile convulsions associated with SARS-CoV-2 infection of the Omicron strain in children may be similar to that of other common respiratory viruses.