The Course of Mild and Moderate COVID-19 Infections-The Unexpected Long-Lasting Challenge.

Background: The course of disease in mild and moderate COVID-19 has many implications for mobile patients, such as the risk of spread of the infection, precautions taken, and investigations targeted at preventing transmission.

Methods: Three hundred thirty-one adults were hospitalized from January 21 to February 22, 2020, and classified as severe (10%) or critical (4.8%) cases; 1.5% died. Two hundred eighty-two (85.2%) mild or moderate cases were admitted to regular wards. Epidemiological, demographic, clinical, chest computed tomography (CT) scan, laboratory, treatment, and outcome data from patient records were analyzed retrospectively.

Results: Patients were symptomatic for 9.82±5.75 (1-37) days. Pulmonary involvement was demonstrated on a chest CT scan in 97.9% of cases. It took 16.81±8.54 (3-49) days from the appearance of the first symptom until 274 patients tested virus-negative in naso- and oropharyngeal (NP) swabs, blood, urine, and stool, and 234 (83%) patients were asymptomatic for 9.09±7.82 (1-44) days. Subsequently, 131 patients were discharged. One hundred sixty-nine remained in the hospital; these patients tested virus-free and were clinically asymptomatic because of widespread persisting or increasing pulmonary infiltrates. Hospitalization took 16.24±7.57 (2-47) days; the time interval from the first symptom to discharge was 21.37±7.85 (3-52) days.

Conclusions: With an asymptomatic phase, disease courses are unexpectedly long until the stage of virus negativity. NP swabs are not reliable in the later stages of COVID-19. Pneumonia outlasts virus-positive tests if sputum is not acquired. Imminent pulmonary fibrosis in high-risk groups demands follow-up examinations. Investigation of promising antiviral agents should heed the specific needs of mild and moderate COVID-19 patients.