Characteristics of Hospitalized Pediatric Patients in the First Five Waves of the COVID-19 Pandemic in a Single Center in Poland-1407 Cases.

This is a single-center, prospective study that compared the clinical presentation and laboratory findings of hospitalized children during the first five waves of the COVID-19 pandemic. Data were collected, according to a standardized questionnaire, from 1407 children from 23 March 2020 to 30 April 2022. Significant differences in clinical courses were found among the five waves probably due to different SARS-CoV-2 variants. The median age was 95.8 months in the first wave versus 14.6-23 months in the others. The number of patients with upper respiratory infection was the highest in the fifth wave (74.4% versus 43.8-56.9% in the others) and for lower respiratory infection in the first wave (50.0% versus 16.4-32.5%). Gastroenterocolitis was more common in the fifth wave (24.4% versus 8.9-16.5%); neurological diagnoses appeared more frequently in the fourth wave (16.6% versus 0.6-9.9%), while anosmia and ageusia were higher in the fifth wave (13% versus 1.5-4%). Life-threatening courses were relatively rare. However, children with pneumonia, dehydration from high fever, gastrointestinal symptoms, loss of smell and taste, and neurological symptoms required hospitalization.