Implement the policy of "one certificate, one code and one card" for all returnees. Returnees should immediately report to the local streets (communities) after arriving in Tianjin, and conduct 1 nucleic acid testing within 24 hours after arriving in Tianjin, and cooperate with the local authorities to do a good job in epidemic prevention and control. People who have lived in other counties (cities, districts and banners) in the city where the middle and high-risk area is located within 14 days shall be under medical observation after arriving in Tianjin 14 days.