Case report: Acute exacerbation of interstitial pneumonia related to messenger RNA COVID-19 vaccination.

Messenger RNA (mRNA) vaccines that protect against COVID-19 are widely used in many countries owing to their high efficacy and safety profiles. Recently, few severe adverse events, such as anaphylaxis and myocarditis, were reported in healthy individuals. The safety of mRNA COVID-19 vaccines has not been adequately studied in patients with interstitial lung disease. We report 2 cases of acute exacerbation of preexisting interstitial pneumonia associated with mRNA COVID-19 vaccination. In both cases, lung disease was stable before the vaccination. Initial responses to steroid therapy were unfavorable, and intravenous cyclophosphamide was administered in both cases. Both patients were diagnosed with vaccine-related exacerbation of interstitial pneumonia based on laboratory results, radiologic features, and the observed clinical course, which lacked other causative events. We suggest that clinicians should note the possibility of acute exacerbation of pneumonia after mRNA COVID-19 vaccination and carefully monitor patients with interstitial lung disease.

COVID-19 Pneumonia Resembling an Acute Exacerbation of Interstitial Pneumonia.

An 84-year-old man was admitted with hypoxemia and ground-glass opacities with traction bronchiectasis in both lungs and mild fibrosis on computed tomography. We first suspected that he had acute exacerbation of interstitial pneumonia and initiated methylprednisolone pulse therapy. On day 4, he was diagnosed with coronavirus disease 2019 (COVID-19) pneumonia. Although the ground-glass opacities were improved with corticosteroid treatment alone, the hypoxemia persisted, and the plasma D-dimer level increased. Anticoagulant therapy was initiated, and the hypoxemia was improved. COVID-19 pneumonia may result in radiological findings similar to those of acute exacerbation of interstitial pneumonia, and corticosteroids and anticoagulant therapy may lead to favorable outcomes.