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

doi:10.5847/wjem.j.1920-8642.2023.105

Abstract

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.

Key words: Olympic Winter Games, Emergency medical service, SARS-CoV-2, COVID-19, Infectious disease, Transmission

Rong Xiong, Jieping Zhou, Wenning Li, Jie Liu, Jing Lou, Sijia Tian, Huixin Lian, Shengmei Niu, Luxi Zhang, Wenhang Li, Jinjun Zhang. Effects of a closed-loop system against SARS-CoV-2 at the Beijing 2022 Olympic Winter Games: a descriptive and modeling study[J]. World Journal of Emergency Medicine, 2023, 14(6): 471-476.

Figures/Tables 6

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Table 1.

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References 10

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Variables	All cases (n=280)
Age, years, median (range)	37 (29-47)
<18, n (%)	2 (0.7)
18-65, n (%)	270 (96.4)
>65, n (%)	8 (2.9)
Male, n (%)	207 (73.9)
Vaccination rate, n (%)	262 (93.5)
Diagnostic time interval, n (%)
Initial screening	93 (33.2)
Closed-loop system time<14 d	181 (64.6)
Closed-loop system time>14 d	6 (2.1)
Diagnosis classification, n (%)
Asymptomatic	270 (96.4)
Mild symptom	10 (3.6)
Continent, n (%)
Asia	76 (27.1)
Europe	187 (66.8)
Americas	15 (5.4)
Oceania	2 (0.7)
Africa	0
Personnel category, n (%)
Athletes	47 (16.8)
Team officials	44 (15.7)
Broadcasters	105 (37.5)
International federations	31 (11.1)
Marketing partners	3 (1.1)
Olympic family	23 (8.2)
Press	19 (6.8)
Workforce	8 (2.9)

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