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. 2023;14(6):471-476.
doi: 10.5847/wjem.j.1920-8642.2023.105.

Effects of a closed-loop system against SARS-CoV-2 at the Beijing 2022 Olympic Winter Games: a descriptive and modeling study

Rong Xiong  1   2 , Jieping Zhou  3 , Wenning Li  3 , Jie Liu  1   4 , Jing Lou  1   5 , Sijia Tian  1 , Huixin Lian  1 , Shengmei Niu  1 , Luxi Zhang  1 , Wenhang Li  3 , Jinjun Zhang  1
Affiliations

Effects of a closed-loop system against SARS-CoV-2 at the Beijing 2022 Olympic Winter Games: a descriptive and modeling study

Rong Xiong et al. World J Emerg Med. 2023.

Abstract

Background: To assess the efficacy of the epidemic prevention measures of the "closed-loop" system adopted by the Beijing 2022 Olympic Winter Games (BOWG).

Methods: We retrospectively collected and analyzed information, including age, sex, nationality, vaccination status, date of diagnosis, and date of entry, from 280 SARS-CoV-2-positive individuals identified during the BOWG. A susceptibility-exposed-infectious-remove model was employed to evaluate the effectiveness of epidemic prevention strategies on controlling the spread of SARS-CoV-2 under different scenarios during the BOWG.

Results: Regarding SARS-CoV-2-positive cases, 97.9% were imported, and 96.4% were asymptomatic. The median age was 37 years (range: 29-47 years), and 73.9% were male, with the majority of cases being broadcasters and European attendees. Regarding vaccination status, 93.5% were fully vaccinated, and six cases were considered to have been infected in the closed-loop system during the BOWG. Assuming that the BOWG adopted a semi-closed-loop management system, the cumulative number of confirmed cases would be 1,137 for quick quarantine measures (3 d later) implemented and 5,530 for delayed quarantine measures (9 d later) implemented. This modeling revealed that stringent pandemic prevention measures and closed-loop management effectively controlled the spread of SARS-CoV-2 during the BOWG.

Conclusion: Imported cases are considered the main risk factor for SARS-CoV-2 transmission during mass gatherings, but a comprehensive closed-loop system could minimize transmission among attendees and general personnel.

Keywords: COVID-19; Emergency medical service; Infectious disease; Olympic Winter Games; SARS-CoV-2; Transmission.

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Conflict of interest statement

Conflicts of interest: The authors declare that they have no competing interests.

Figures

Figure 1
Figure 1
Daily new confirmed SARS-CoV-2 positive cases during the Beijing 2022 Olympic Winter Games (BOWG). A total of 280 SARS-CoV-2 positive cases within the closed-loop were enrolled in this study from January 1, 2022, to February 20, 2022, while 108 residents affected SARS-CoV-2 were detected in Beijing community.
Figure 2
Figure 2
Modified SEIR model for COVID-19 outside the closed-loop system of the Beijing 2022 Olympic Winter Games. SEIR: susceptibility-exposed-infectious-remove.
Figure 3
Figure 3
Diagnostic time interval of SARS-CoV-2 positive cases in the closed-loop system of the BWOG.
Figure 4
Figure 4
Simulation of COVID-19 outside the closed-loop system of the BWOG.
Figure 5
Figure 5
Scenario simulations for semi-closed-loop (Isolation measures were taken after 3 d or 9 d).
See this image and copyright information in PMC

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