Epidemiological and Clinical Characteristics of Pediatric COVID-19 in the Tertiary Care System in Thailand: Comparative Delta and pre-Delta Era.

Background: Few studies had focused on the epidemiological and clinical characteristics of pediatric COVID-19 (SARS-CoV-2) during Delta and pre-Delta eras in Asia, despite it being a pandemic. Objective: To study the epidemiological and clinical characteristics of three waves of pediatric COVID-19 infections in a tertiary-care setting in Thailand. Methods: This retrospective study reviewed all PCR-confirmed pediatric (0-18 years of age) COVID-19 infections between January 13, 2020, and October 31, 2021, in a tertiary care system in Thailand. Results: 1,019 patients, aged 0.02 - 18 years, 552 (54.2%) male, and 467 (45.8%) female, with a median age of 9.2 years, were enrolled. Asymptomatic cases accounted for 35.7%, of which 106 (18.9%) had abnormal chest X-ray findings. Most cases were classified as having mild clinical symptoms, with only 8 (0.8%) and 4 (0.4%) developing a severe and critical illness, respectively. There were no deaths. The Delta variant appeared more transmissible than previous ones, but we did not see any difference in disease severity. Upper respiratory tract symptoms were predominant, while few cases had lower respiratory tract involvement. The sensitivity and specificity of dyspnea symptoms to predict radiologically confirmed pneumonia were 14% and 95%, respectively, with a likelihood ratio of 3.37. The overall prognosis was good, with only 13 (1.3 %) needing respiratory support. All cases showed clinical improvement with a decent recovery. Conclusion: Pediatric COVID-19 during the Delta variant predominance era generally appeared more transmissible but benign. One-fifth of cases had pneumonia, but few cases needed respiratory support. Prevention remains important for disease control.