Acute and Postacute Clinical Characteristics of Coronavirus Disease 2019 in Children in Japan

Abstract

Background: The clinical features of coronavirus disease 2019 (COVID-19) in children have been changing because of the emergence and rapid spread of variants of concern (VOC). The increase in cases infected with VOC has brought concern with persistent symptoms after COVID-19 in children. This survey aimed to analyze the clinical manifestations and persistent symptoms of pediatric COVID-19 cases in Japan. Methods: We analyzed the clinical manifestations of pediatric COVID-19 cases reported between February 2020 and April 2022 in Japan, using a dedicated database updated voluntarily by the members of the Japan Pediatric Society. Using the same database, we also analyzed persistent symptoms after COVID-19 in children who were diagnosed between February 2020 and November 2021. Results: A total of 5411 and 1697 pediatric COVID-19 cases were included for analyzing clinical manifestations and persistent symptoms, respectively. During the Omicron variant predominant period, the percentage of patients with seizures increased to 13.4% and 7.4% in patient groups 1–4 and 5–11 years of age, respectively, compared with the pre-Delta (1.3%, 0.4%) or Delta period (3.1%, 0.0%). Persistent and present symptoms after 28 days of COVID-19 onset were reported in 55 (3.2%). Conclusions: Our survey showed that the rate of symptomatic pediatric COVID-19 cases increased gradually, especially during the Omicron variant predominant period, and a certain percentage of pediatric cases had persistent symptoms. Certain percentages of pediatric COVID-19 patients had severe complications or prolonged symptoms. Further studies are needed to follow such patients.

Differences in Clinical Presentation of COVID-19 in Children Hospitalized During Domination of Early (BA.1, BA.2) and Late (BA.5, BA.2.75, BQ.1 and XBB.1.5) SARS-CoV-2 Omicron Subvariants

“…9 In our cohort, fever was significantly more frequent during LO period (87% compared to 79% during EO), but the prevalence of febrile seizures was low and did not differ according to the analyzed periods (1.5% during LO, and 0.87% during EO). Fever was found by other authors to occur more frequent during the Omicron wave compared to previous variants, 8,9,11 which may lead to an increase in the incidence of febrile seizures. In addition, most studies reported that children suffering from COVID-19 during the Omicron wave were significantly younger than in previous periods, [10][11][12] which may contribute to a more frequent occurrence of febrile seizures or croup, which are typically seen more often in younger children.…”

Clinical Practice Patterns, Health Resource Use and Risk Factors for Severe Conditions Among Children Hospitalized With COVID-19 in Japan

“…22,23 Thirdly, the increase in febrile seizure and gastrointestinal symptoms among children with COVID-19 during Wave VI and VII contributed to the elevated use of ambulances, antiepileptics and antiemetics, as well as higher levels of creatinine phosphokinase and aspartate aminotransferase in our findings. 5–7…”

“…22,23 Thirdly, the increase in febrile seizure and gastrointestinal symptoms among children with COVID-19 during Wave VI and VII contributed to the elevated use of ambulances, antiepileptics and antiemetics, as well as higher levels of creatinine phosphokinase and aspartate aminotransferase in our findings. [5][6][7] The decreasing trends in total healthcare costs and length of hospital stay reflected the changes in the discharge criteria defined by the Ministry of Health, Welfare and Labor and local governments in Japan. During the earlier waves, the discharge criteria were strict, which included 2 consecutive negative results of a nucleic acid amplification test or antigen test following symptom improvement for inpatients with nonsevere COVID-19.…”

“…Indeed, previous studies reported an increase in hospitalizations due to COVID-19, with most children presenting symptoms such as fever, vomiting and seizures. [5][6][7] However, the trends in treatment patterns, health resource use and medical costs, as well as risk factors for severe COVID-19 among pediatric inpatients, remain unclear.…”

Adverse reactions in young children receiving the coronavirus disease 2019 vaccine

“…The prevalence of seizures in children aged 1-4 years, which was 1.3% before the Delta variant outbreak, increased to 13.4% during the Omicron variant period. 33 Infants and preschool-aged children accounted for 65.1% of severe and moderate pediatric cases during the Omicron variant period. Between January and September 2022, a total of 62 deaths due to COVID-19 were confirmed in individuals under the age of 20, with children under 5 years old representing approximately half of these cases.…”