Fig. 4
From: Cough and sputum in long COVID are associated with severe acute COVID-19: a Japanese cohort study
The relationship between prolonged cough and sputum during follow-up periods and the severity of acute COVID-19 infection. A, B) Longitudinal changes in both prolonged cough and sputum were analyzed using the Kaplan–Meier estimator in patients with different COVID-19 severity (mild, moderate I, moderate II and severe). C, D) Longitudinal changes in both prolonged cough and sputum were analyzed using the Kaplan–Meier estimator in patients with or without oxygen therapy during acute COVID-19 infection. Group 1: Patients without oxygen therapy. Group 2: Patients who needed oxygen therapy