After fulfilling the Chinese current criteria for discharge, it may still take a few days for the immune system to completely eliminate the residual viruses in the body [7]. During this period, the virus may rebound and test positive, but the patients were asymptomatic and chest CT showed no deterioration. If the patients’ immunity decreases, there is a risk of a relapse. On 6 February 2020, a recovered COVID-19 patient in Changde (Hunan province, China) had a fever and cough 2 days after discharge, and chest CT showed worsened status [12].