Occupational Characteristics and Management Measures of Sporadic COVID-19 Outbreaks From June 2020 to January 2021 in China: The Importance of Tracking Down "Patient Zero"

Abstract

There are occupational disparities in the risk of contracting COVID-19. Occupational characteristics and work addresses play key roles in tracking down "patient zero." The present descriptive analysis for occupational characteristics and management measures of sporadic COVID-19 outbreaks from June to December 2020 in China offers important new information to the international community at this stage of the pandemic. These data suggest that Chinese measures including tracking down "patient zero," launching mass COVID-19 testing in the SARS-CoV-2-positive areas, designating a new high- or medium-risk area, locking down the corresponding community or neighborhood in response to new COVID-19 cases, and basing individual methods of protection on science are effective in reducing the transmission of the highly contagious SARS-CoV-2 across China.

Keywords: COVID-19 disease; occupational characteristics; patient zero; person-to-person transmission; protective measures; severe acute respiratory syndrome coronavirus 2; sporadic cases.

Figure 1

Geographical and occupational distribution of local sporadic outbreak cases with COVID-19 from June to December 2020. Five cities (Dalian, Tianjin, Qingdao, Kashgar, and Shanghai) reported the “patient zero.” For the outbreak in Kashgar and Shanghai, the source of the epidemic was frozen or wet containers outside the border and their “patient zero” was container stevedore who was asymptomatic. Plaza business hall staff (1) in Urumqi (July 15), supermarket employees (1) in Shenzhen (August 14), truck driver (1) in Hong Kong (July 26), Food delivery staff (1) and food production workers (8) in Beijing (June 21) were diagnosed as confirmed cases.

Figure 2

The graph's left-right axis (dates from June to December 2020) is used as a timeline of the key events and dynamic profile of “patient zero” during the local sporadic COVID-19 outbreak. From June to December 2020, five cities in China had reported over nine “patient zero,” including two confirmed cases and seven asymptomatic cases. On October 27, NHC issued Q&A of COVID-19 prevention and control Technology Guide for cold chain food production and COVID-19 prevention and Control Disinfection Technology Guide for cold chain food. The contents include hygiene management measures at the source of cold chain goods, prevention and control requirements in the process of production and processing, prevention and control requirements in the process of sales and operation, cleaning and disinfection operations in the process of cold chain food production and processing and precautions for disinfection of equipment or surfaces of environmental objects. On November 27, the Chinese Ministry of Transport issued a comprehensive guideline to lower the risk of virus transmission via cold chain logistics.

Figure 3

ARS-CoV-2 detection on imported frozen raw foods and their packaging materials across China. During the outbreak in Beijing, five fish swab samples related to imported cold chain food (Salmon) tested positive for SARS-CoV-2 nucleic acid in Xinfadi market. As for the outbreak in Qingdao, the live SARS-CoV-2 virus was successfully isolated from the imported frozen cod package surfaces. The SARS-CoV-2 was also found on frozen food surfaces, packaging materials and food storage environments in many cities, for example Dalian (July 3), Xiamen (July 3) Shenzhen (August 12), etc.