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Coronavirus disease 2019 outbreak in Beijing's Xinfadi Market, China: a modeling study to inform future resurgence
Xiao-Li Wang1,2,3, Xin Lin4, Peng Yang1,2
1Beijing Research Center for Preventive Medicine, Beijing Center for Disease Prevention and Control, Beijing, China.
Insights
Rapid response to the Beijing COVID-19 outbreak, including market source identification and expanded testing, significantly limited transmission. Delays in implementing non-pharmaceutical interventions (NPIs) and quarantine measures would have drastically increased case numbers and containment time.
Area of Science:
- Epidemiology
- Public Health
- Infectious Disease Modeling
Background:
- Beijing experienced a COVID-19 resurgence linked to the Xinfadi market in June 2020.
- Non-pharmaceutical interventions (NPIs) were crucial for controlling the outbreak.
- The study assesses the effectiveness of Beijing's response to the Xinfadi market outbreak.
Purpose of the Study:
- To evaluate the effectiveness of public health interventions during the Beijing COVID-19 outbreak.
- To inform future strategies for controlling infectious disease resurgence.
Main Methods:
- A modified susceptible-exposed-infectious-recovered (SEIR) model was employed.
- The model evaluated various scenarios concerning NPIs and containment.
- Outcomes measured included transmission magnitude and containment duration.
Main Results:
- Delayed NPI implementation (3-14 days) could have increased cases 3-28 fold.
- Failure to quarantine key populations or close contacts would have significantly amplified transmission.
- Absence of expanded nucleic acid screening would have led to 1.6-fold greater transmission and delayed containment by 32 days.
Conclusions:
- Timely NPI implementation is critical for controlling COVID-19 outbreaks.
- Specific interventions like quarantine and widespread screening are highly effective.
- Findings offer evidence for optimizing outbreak response strategies globally.
Background:
A local coronavirus disease 2019 (COVID-19) case confirmed on June 11, 2020 triggered an outbreak in Beijing, China after 56 consecutive days without a newly confirmed case. Non-pharmaceutical interventions (NPIs) were used to contain the source in Xinfadi (XFD) market. To rapidly control the outbreak, both traditional and newly introduced NPIs including large-scale management of high-risk populations and expanded severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PCR-based screening in the general population were conducted in Beijing. We aimed to assess the effectiveness of the response to the COVID-19 outbreak in Beijing's XFD market and inform future response efforts of resurgence across regions.
Methods:
A modified susceptible-exposed-infectious-recovered (SEIR) model was developed and applied to evaluate a range of different scenarios from the public health perspective. Two outcomes were measured: magnitude of transmission (i.e., number of cases in the outbreak) and endpoint of transmission (i.e., date of containment). The outcomes of scenario evaluations were presented relative to the reality case (i.e., 368 cases in 34 days) with 95% Confidence Interval (CI).
Results:
Our results indicated that a 3 to 14 day delay in the identification of XFD as the infection source and initiation of NPIs would have caused a 3 to 28-fold increase in total case number (31-77 day delay in containment). A failure to implement the quarantine scheme employed in the XFD outbreak for defined key population would have caused a fivefold greater number of cases (73 day delay in containment). Similarly, failure to implement the quarantine plan executed in the XFD outbreak for close contacts would have caused twofold greater transmission (44 day delay in containment). Finally, failure to implement expanded nucleic acid screening in the general population would have yielded 1.6-fold greater transmission and a 32 day delay to containment.
Conclusions:
This study informs new evidence that in form the selection of NPI to use as countermeasures in response to a COVID-19 outbreak and optimal timing of their implementation. The evidence provided by this study should inform responses to future outbreaks of COVID-19 and future infectious disease outbreak preparedness efforts in China and elsewhere.
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