Cancelled by the investigator Clinical trial for umbilical cord blood CIK and NK cells in the treatment of mild and general patients infected with novel coronavirus pneumonia (COVID-19)

INTERVENTION: Control group:conventional therapy;CIK group:Umbilical cord blood CIK cells (1.6×10E8/kg) were injected twice every other day.;NK group:Umbilical cord blood NK cells (1.6×10E8/kg) were injected twice every other day.; CONDITION: Novel Coronavirus Pneumonia (COVID‐19) PRIMARY OUTCOME: Status of immune function;The time of nucleic acid turns to negative;Length of stay in‐hospital; SECONDARY OUTCOME: The incidence rate of complication; INCLUSION CRITERIA: 1. New‐type coronavirus infection is diagnosed as mild or common (diagnosed according to the "Notice on the Issuance of a New Coronavirus‐Infected Pneumonia Diagnosis and Treatment Plan (Trial Implementation of the Sixth Edition)") or patients with poor immune function (cured discharged patients but peripheral hemolymph Cell count and classification are abnormal). 2. Aged 18‐65 years; 3. Sign informed consent.