A positive novel coronavirus nucleic acid test or antigen test usually indicates that the patient has novel coronavirus. The disease is contagious, mainly through respiratory tract and close contact, and may also be transmitted through aerosol. People are generally susceptible and infected quickly. Patients who are positive for novel coronavirus nucleic acid or antigen live in a relatively closed environment, novel coronavirus suspended particles may exist in the air, and novel coronavirus residues may exist in household products, which are easy to be infected. The infection time is 1-3 days, and the exact time cannot be determined.