Novel coronavirus is highly contagious and harmful. Have you had any direct or indirect contact with infected people in COVID-19 recently? For the health and social safety of citizens and their families, in accordance with the provisions of laws and regulations such as the Law on the Prevention and Control of Infectious Diseases, the Emergency Regulations for Public Health Emergencies and the requirements of epidemic prevention and control, the CDC will come to the door to detect nucleic acids or take them away for isolation.