Abstract
An 82-year-old man diagnosed with interstitial lung disease through computed tomography (CT) 1 year prior received a bivalent (tozinameran and famtozinameran) mRNA COVID-19 vaccine. He developed respiratory symptoms 1.5 months later, and chest high-resolution CT revealed new ground-glass opacities showing traction bronchiectasis. Transbronchial lung cryobiopsy revealed organizing acute lung injury and fibrosis with architectural destruction. The patient was diagnosed with an acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF). The bivalent mRNA COVID-19 vaccination was determined as the cause of the AE-IPF based on detailed medical history and examination findings. High-dose corticosteroid therapy improved the patient's symptoms and radiological findings.