393. Comparison of COVID-19 Associated Complications in Children during the First and Second Omicron Waves in Taiwan

BACKGROUND: In early 2022, the Omicron variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Taiwan and caused two waves of COVID-19 outbreaks throughout the year. The emergence of the Omicron variant in Taiwan has led to an increased incidence of COVID-19 associated complications in children. This study aims to compare COVID-19 associated complications in children admitted during the peak of the first wave (late May, 2022, BA.2 predominance) and the second wave (early October, 2022, BA.5 predominance) of the Omicron-driven outbreaks in Taiwan. METHODS: This retrospective, single-center, observational study was conducted at China Medical University Children's Hospital (CMUCH), a tertiary hospital in central Taiwan. The study population included children under 18 years of age who were admitted with a confirmed SARS-CoV-2 infection between May 1 and October 31, 2022. Medical records of these children were collected. The study period was divided into two periods based on the peak of the outbreak: May 1 to June 30, 2022 and September 1 to October 31, 2022. During these periods, the COVID-19 associated complications of hospitalized children were compared. RESULTS: A total of 228 pediatric patients with SARS-CoV-2 infection were included, with 145 (63.6%) from the first wave and 83 (36.4%) from the second wave. The median age (IQR) was similar between the two waves [18 (6-43) months vs. 16 (5-62) months, p = 0.796]. The proportion of patients with underlying comorbidities was similar between the two waves (7.6% vs. 12.1%, p = 0.262). Patients in the second wave had a lower ICU admission rate (16.6% vs. 9.6%, p = 0.148). The proportion of patients with bacterial coinfection was higher in the second wave (15.9% vs. 24.1%, p = 0.126). The proportion of patients with febrile convulsion (13.8% vs. 16.9%, p = 0.531), myositis (5.5% vs. 2.4%, p = 0.334), and croup (11.0% vs. 16.9%, p = 0.148) were similar between the two waves. CONCLUSION: There was no significant difference in the frequency of admission for COVID-19 associated complications between the BA.2 and BA.5 predominance periods. However, it was observed that children admitted during the second wave had a lower rate of ICU admission and a higher rate of bacterial coinfection. DISCLOSURES: All Authors: No reported disclosures