The authors present a case report of an otherwise healthy, fully immunized 12-year-old girl who had a critical course of COVID-19 infection with acute respiratory failure. The epidemiologic history was positive for COVID-19, and she tested PCR positive resulting from a nasopharyngeal swab. She was presented with fever and cough to a regional pediatric department, and she was immediately intubated and transferred to a pediatric ICU in a University Hospital. CT of the thorax revealed bilateral consolidation with the tree-in-bud signs. Her condition required artificial ventilation support for 13 days. Remdesivir, pronation, high dose Ascorbic acid with Thiamine, and combined antimicrobial therapy were successfully used. The patient made a full clinical recovery. This case report is unique because of a very scarce critical course of COVID-19 infection in children. It demonstrates the successful use of a combined therapeutic approach with artificial ventilation, pronation, Remdesivir, and combined antimicrobial therapy. Clinical symptoms, laboratory results, imaging methods, and therapeutic attitude are mentioned to share our experience with the medical community.