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.