Human coronavirus HKU1 (HCoV-HKU1)-associated acute respiratory distress syndrome: A case report.

Background: Human coronavirus HKU1 (HCoV-HKU1) is a known cause of mild to moderate respiratory infections. However, in vulnerable individuals such as the elderly and immunocompromised, it may result in severe lower respiratory tract involvement, including acute respiratory distress syndrome (ARDS). This report presents a rare case of HCoV-HKU1-induced ARDS with multi-organ complications. Case presentation: A 70-year-old man with hypertension, type 2 diabetes mellitus, and recent abdominal aortic aneurysm repair presented with progressive dyspnea and intermittent hemoptysis. On examination, he exhibited tachypnea, hypoxemia, and bilateral basilar crackles. Laboratory workup showed leukocytosis, anemia, acute kidney injury, and elevated inflammatory markers. Despite supportive therapy, his condition worsened, requiring intubation for severe ARDS. A nasopharyngeal respiratory PCR panel was positive for HCoV-HKU1. He received empirical broad-spectrum antibiotics, corticosteroids, and Remdesivir. His respiratory status improved, allowing extubation. However, his hospital course was complicated by worsening renal function requiring dialysis and new-onset chest pain with elevated troponin levels. Coronary angiography revealed 60 % proximal left circumflex artery stenosis. After a month-long hospitalization, he was discharged but remained dialysis-dependent. Conclusion: This case emphasizes that HCoV-HKU1 can cause life-threatening ARDS and systemic complications in elderly patients with comorbidities. Given its potential for severe outcomes, it should be considered in the differential diagnosis of viral pneumonia and ARDS, particularly when other pathogens are excluded. Prompt identification and aggressive supportive management are vital, though long-term sequelae such as dialysis dependence may persist despite clinical recovery.