Blood Eosinophils Matter in Post-COVID-19 Pneumonia

Background: Even after the development of vaccines, SARS-CoV-2 continues to cause severe pneumonia all over the world. Consequently, in order to improve the management of patients and optimize the use of resources, predictors of disease severity and lung complications after COVID-19 pneumonia are urgently needed. Blood cell count is an easily available and reproducible biomarker. With this study, we aimed to explore the role of eosinophils in predicting disease behavior and pulmonary sequelae at first follow-up with computed tomography (CT). Methods: we evaluated blood cell count and other inflammatory markers, both at baseline and during hospitalization, in a large population of hospitalized COVID-19 patients. Results: 327 patients were finally enrolled, 214 were classified as low-intensity medical care (LIMC) and 113 as high-intensity medical care. Eosinophils were higher at discharge in the HIMC group [0.1 (0–0.72) vs. 0.05 (0–0.34) × 109/L; p < 0.0001]. Moreover, in the multivariable analysis, age ≥ 62 years (OR 1.76 (1.05–2.8) p = 0.03) and Δ eosinophils ≥ 0.05 (OR 1.75 (1.05–2.9) p = 0.03) were two independent predictors of residual lung abnormalities in the whole patient population at first follow-up. Conclusions: an eosinophil increase during hospitalization could be a potential predictor of pulmonary sequelae in surviving patients after COVID-19 pneumonia.