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The mobility gap: estimating mobility thresholds required to control SARS-CoV-2 in Canada
Kevin A Brown1, Jean-Paul R Soucy2, Sarah A Buchan2
1Public Health Ontario (Brown, Buchan, Daneman); Dalla Lana School of Public Health (Brown, Soucy, Buchan, Sturrock, Berry), and The Institute for Health Policy, Management, and Evaluation (Stall, Jüni, Daneman), University of Toronto; Applied Health Research Centre, St. Michael's Hospital (Jüni); Sinai Health System and the University Health Network (Stall); Women's College Hospital (Stall); Department of Medicine (Stall, Daneman), University of Toronto, Toronto, Ont.; Communications Research Centre Canada (Ghasemi); Public Health Agency of Canada (Gibb); Ottawa Hospital Research Institute (MacFadden), Ottawa, Ont.; Division of Infectious Diseases (Daneman), Sunnybrook Research Institute, Toronto, Ont. kevin.brown@utoronto.ca nick.daneman@sunnybrook.ca.
Smartphone mobility data reveals that a significant mobility gap existed in Canada from July to December 2020. Lowering mobility is crucial for controlling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread.
Area of Science:
- Epidemiology
- Public Health
- Data Science
Background:
- Nonpharmaceutical interventions are key to controlling SARS-CoV-2 until herd immunity is reached.
- Anonymized smartphone mobility data was used to assess control measures.
- The study quantified the mobility threshold and gap for SARS-CoV-2 control.
Purpose of the Study:
- To quantify the mobility threshold needed to control SARS-CoV-2.
- To determine the mobility gap relative to observed mobility.
- To evaluate the impact of mobility on SARS-CoV-2 case growth rates.
Main Methods:
- A time-series study analyzed weekly SARS-CoV-2 incidence in Canada (Mar. 2020–Mar. 2021).
- Weekly growth rate was the primary outcome, assessed using log-normal regression.
- Smartphone mobility data was used to calculate the mobility threshold and gap.
Main Results:
- Each 10% increase in the mobility gap correlated with a 25% rise in SARS-CoV-2 weekly case growth.
- The mobility threshold varied seasonally, from 69% in summer to 54% in winter 2021.
- A mobility gap persisted in Canada from July to December 2020.
Conclusions:
- Mobility levels strongly predict SARS-CoV-2 case growth.
- Sustained low mobility is necessary for controlling the virus through spring 2021.
- Smartphone mobility data can inform public health decisions on physical distancing measures.
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