Study on the COVID 19 infection status, prevention and control strategies among entry people in Shenzhen

Background The overseas COVID-19 confirmed cases continue to rise for months, while people overseas prefer to return China at present. It is risky to have a large number of imported cases which may cause a relapse of COVID-19 outbreak. In order to prevent imported infection, Shenzhen government has implemented the closed-loop management strategy by taking nucleic acid testing (NAT) for severe acute respiratory syndromes coronavirus 2 (SARS-CoV-2) and requiring14-days medical observation for individuals with overseas tour history (Hong Kong, Macao, Taiwan province and other countries) within 14 days. Our study aim to describe the status of COVID-19 infection among entry people in Shenzhen, and evaluate the effect of closed-loop management strategy. Methods We made a descriptive study and risk analyze by the entry time, reported time, local confirmed cases in origin countries. The NAT were completed in Shenzhen center for disease control and prevention (CDC), ten district-level CDCs, as well as fever clinics. Results A total of 86,844 people overseas entered Shenzhen from January 1 to April 18, 2020, there were 39 imported cases and 293 closed contacts. The infection rate of entry people was 4.49‰ (95% CI: 3.26‰ − 6.05‰). 14 imported cases (35.9%) came from the UK, 9 (23.08%) came from the US. Entry people from the US since Mar 9 or from the UK since Mar 13 are the high-risk population. As of July 17, there have been no new confirmed cases in Shenzhen for 153 days, and the number of confirmed case, close contact, and asymptomatic case are 0. So the closed-loop management is effective to prevent imported infection and control domestic relapse. The distribution of entry time and report time for imported cases overseas was similar. So it is important to take closed-loop management at the port. Conclusions The risk of imported infection from the US and UK were higher that other countries and regions in Shenzhen. The closed-loop management is effective to prevent imported infection and control domestic relapse. Every country is closely connected under the background of globalization. In order to control COVID-19 outbreak, we need the collaboration and cooperation at the global, national, and subnational levels to prevent, detect, and respond effectively.