Covid-19 and the post-Covid-19 status in children is currently a health issue that requires further research. The most common organ damage caused by Covid-19 is the lungs. This study aims to describe the clinical and subclinical characteristics and results of pneumonia treatment in children after Covid-19 infection during 3 months at the Pediatric Center, Thai Nguyen National Hospital in 2022. The study on 103 children who met the criteria showed that the group of children from 1-5 years old accounted for the highest rate of 72.8%, the male/female ratio = 1.5/1. The main clinical symptoms of pneumonia after Covid-19 infection are cough (98.1%), wheezing (96.1%), rales in the lungs (95.1%), fever (66.0%); In addition, the symptoms outside the respiratory organs also accounted for a significant proportion, such as: anorexia (79.6%), sleep disorders (51.5%), anemia (20%), diarrhea (12.6%). Nutritional status including both malnutrition and overweight /obesity increased the severity of pneumonia and chest X-ray lesions, the difference was statistically significant p<0.05. The use of antibiotics before hospital admission did not reduce the severity of pneumonia as well as the need to use multiple courses of treatment in the hospital.