Since the beginning of the pandemic, many reports have pointed to age as the most important risk factor for severe COVID-19 in adults, but this relationship is less clear in children. Between March 2020 and April 2022, 1405 pediatric COVID-19 patients were included in our prospective study, which aimed to analyze the disease's characteristics in three age groups: infants, toddlers (1-5 years), and children (5-18 years). We observed male prevalence of the disease in infants and toddlers compared to female prevalence in children. Comorbidities appeared most often in children. In the first pandemic wave, the vast majority of pediatric patients were children, but later, the percentage of infant and toddler patients increased significantly. A total of 74% of hospitalized children were younger than five years. Upper respiratory tract symptoms were most common in infants and toddlers, and lower respiratory tract symptoms and gastroenterocolitis were more common in children. Neurological symptoms appeared similarly in all age groups. The activities of ALT, CK, and LDH were the most elevated in infants, along with D-dimers. The median length of hospitalization fluctuated between three and four days and was highest in infants. Severe courses were more common in adolescents.
Keywords: COVID-19; SARS-CoV-2; age; children; clinical presentation.