KRT5 and pemphigus foliaceus: Recent efforts have revealed several histopathological features conserved across various cohorts of respiratory PASC and PASC-PF patients including the prolonged reduction in alveolar epithelial cells (38), maintenance of Krt8hi and Krt5+ dysplastic progenitors (5, 8), and the persistence of various immune cell populations in the lungs (9, 10, 59).