Persistence of lymphocytopenia with CT abnormalities among patients with critical H7N9 swine-origin influenza A virus infection

H7N9 is an emerging pathogen with associated morbidity and mortality, and a broader understanding of the chest radiographic characteristics associated with human H7N9 infections is needed. This study was performed to determine the time course of recovery from lymphocytopenia and resolution of pneumonitis of critical H7N9 infection patients. We performed chest X-ray and computed tomography (CT) for patients with H7N9 influenza. Lesion patterns, distributions, and changes at follow-up chest X-ray and/or CT were investigated. The time to progression on chest CT image, and the time to resolution of the chest CT findings were assessed. Lymphocytopenia was a common laboratory test abnormality. The most common CT findings were lobar consolidation with air bronchogram and ground-glass opacities. For 7 recovering patients, the time to resolution of the chest CT findings was 10-90 days. Fibrosis and traction bronchiectasis were the main features on the CT scans of recovering patients. Interestingly, the time to recovery from lymphopenia was highly consistent with time to resolution of the chest CT findings. We have shown the presence of radiographic abnormalities among H7N9 patients. Monitoring of the variation of lymphocytes for H7N9 patients has important clinical significance, especially for prediction of the resolution of pneumonitis.