








key: cord-307732-sdstnm9i
authors: Yang, Kai; Wang, Lingwei; Li, Furong; Chen, Dandan; Li, Xi; Qiu, Chen; Chen, Rongchang
title: The influence of preventive strategies on COVID-2019 epidemic in Shenzhen, China
date: 2020-04-16
journal: Eur Respir J
DOI: 10.1183/13993003.00599-2020
sha: 
doc_id: 307732
cord_uid: sdstnm9i

Early identification of imported cases, prevention of family clustering transmission, preventive measures in the public area and strict infection control procedure in hospitals were crucial for successful prevention of COVID-19 in Shenzhen, China.

Hubei in December 2019, and spread to all provinces in China and more than 90 countries in the next 2 months [1] [2] [3] [4] [5] . By March 7, 2020, COVID-19 has infected more than 90000 cases and led to more than 3000 deaths [6] . There are about 20 million people living in Shenzhen, of which the external population from the internal area of China, including Hubei province, account for a large proportion. High population density, high proportion of external population and high mobility may increase the possibility of COVID-19 outbreak [7, 8] . The first COVID-19 patient in Shenzhen was admitted on January 9, 2020, and 419 cases have been confirmed by March 7, 2020 , which ranked the top cities outside Wuhan. Most of these patients were imported cases from Hubei province, and there was no large-scale transmission and nosocomial infection in Shenzhen until now.

Therefore, the purpose of this study was to analyze the epidemiology and preventive strategies in Shenzhen in order to understand the main transmission route and effective preventive strategies in cities with risk of imported cases, which may provide clue for better preventing outbreak of potential respiratory infectious disease, such as COVID-19 in cities with heavy population density and high proportion of external population.

The data of this study were downloaded from the data open-platform of Shenzhen government (https://opendata.sz.gov.cn). The number of confirmed cases of COVID-19 began to be released daily on January 19, 2020, and 419 cases have been confirmed by March 7, 2020. Compared with the reports from Wuhan, Hubei [9] , the age of infected population in Shenzhen was younger and decreasing gradually, in which 33 patients were children. Familial clustering was an important feature of COVID-19 [10] . In Shenzhen, 232 COVID-19 patients (232/419, 55.4%) came from 86 families, 15 of which had more than 3 patients, indicating that local transmission in the family environment was important route of transmission.

Based on the daily new cases, three phases were classified: the slow increase phase from January 19 to January 28, the rapid increase and plateau phase from January 29 to February 5, and the decline phase since February 6 ( Figure 1 ). Almost all cases (61/63, 96.8%) in slow increase phage were patients from Hubei, and 2 cases were family members of these patients, indicating that main source of COVID-19 patients was imported from Hubei province. Compared with the previous period, majority of the patients (174/228, 76.3%) in the rapid increase and plateau phase were still from Hubei, but infection related to contact with Hubei patients (27/228, 11.8%), non-Hubei patients (12/228, 5.3%) and no contact history (14/228, 6.1%) increased. In the decline phase, the number of daily new confirmed cases decreased All medical staff involved in the management of COVID-19 patients implemented infection control procedures. For the general population, people entering the hospital were asked to wear masks and take body temperature. The hospital environment was disinfected timely and regularly, hand-washing equipment and disinfectants were equipped in multiple places, and indoor air ventilation was strengthened.

As early as January 19, when the National Health Commission announced the first imported case in Shenzhen, Shenzhen began to take temperature for people in main city entrances to screen imported cases, which was also widely used in the prevention of other respiratory infectious diseases, such as influenza in United States and SARS in China [11, 12] . After the release of the first (highest) level response to major public health emergencies in Guangdong on January 23, all

Chinese new year's entertainments were cancelled, and many public places were temporarily closed in Shenzhen, such as market, library, gymnasium. Other necessary public places needed to be disinfected regularly, including airport, station, port, freeway entrance, urban traffic, community entrance. The employees in these places needed to have health examinations. People came to these places needed to wear masks and take body temperature. These measures were important for blocking the spread of COVID-19

Millions of people returned to Shenzhen from all over the country after Chinese new

year's holiday, which may lead to the imported cases and potential transmission.

Therefore, strengthened measures were implemented in February 2, which included isolating all the new arrival people came from epidemic area for medical observation for 14 days, informing all people in the living communities once there were confirmed cases, using of big data and information technology to track the places in the last 14 days and identify the contacted persons of the confirmed cases.

The preventive strategies and measures implemented in Shenzhen were supposed to block the transmission of COVID-2019. The newly diagnosed COVID-19 cases reached its peak around January 31, which was 7 days after the peak date of cases arrived at Shenzhen (mainly patients in incubation period from Hubei) and around 10 days after the serial early preventive strategy implemented. Taking account of the incubation period (mostly 3-7 days, with mean of 3.7 days) and the time between symptom onset and confirm of the diagnosis (6 day on average) [13, 14] 

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None declared.

