Exploring strengths and weaknesses of mobility inference from mobile phone data vs. travel surveys

Buchan

et al. 2021

CMAJ

BACKGROUND: Nonpharmaceutical interventions remain the primary means of controlling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) until vaccination coverage is sufficient to achieve herd immunity. We used anonymized smartphone mobility measures to quantify the mobility level needed to control SARS-CoV-2 (i.e., mobility threshold), and the diference relative to the observed mobility level (i.e., mobility gap). METHODS:We conducted a time-series study of the weekly incidence of SARS-CoV-2 in Canada from Mar. 15, 2020, to Mar. 6, 2021. The outcome was weekly growth rate, defined as the ratio of Early release, published at www.cmaj.ca on April 7, 2021. Subject to revision.

Section: Discussionmentioning

confidence: 99%

Section: Mobility Measuresmentioning

confidence: 99%

The mobility gap: estimating mobility thresholds required to control SARS-CoV-2 in Canada

Buchan

et al. 2021

CMAJ

“…For each mobility measure, the baseline level was the median value during the 5-week period from Jan 3–Feb 6, 2020, a period 1-month prior to the first confirmed case of community transmission in Canada (March 5 in British Columbia) and prior to first the first school closures in Canada (March 15 in Ontario). The residential index values were rescaled so that levels in the baseline period represented 100%, with a range from 0% (no non-residential mobility) to values greater than 100% (8,9). Park visit volumes were similarly rescaled.…”

Section: Methodsmentioning

confidence: 99%

“…As with any infectious disease, contact rates are a primary driver of COVID-19 transmission (5). Mobility measures capturing human activity through anonymized tracking of smartphones are believed to be reasonable proxies of contact rates outside of one’s own home; these measures can provide more timely and reliable sources of information on contact rates compared to time-use surveys or contact tracing (6–8).…”

Section: Introductionmentioning

confidence: 99%

The mobility gap: estimating mobility levels required to control Canada’s winter COVID-19 surge

et al. 2021

Preprint

BackgroundNon-pharmaceutical interventions remain a primary means of suppressing COVID-19 until vaccination coverage is sufficient to achieve herd immunity. We used anonymized smartphone mobility measures in seven Canadian provinces to quantify the mobility level needed to suppress COVID-19 (mobility threshold), and the difference relative to current mobility levels (mobility gap).MethodsWe conducted a longitudinal study of weekly COVID-19 incidence from March 15, 2020 to January 16, 2021, among provinces with 20 COVID-19 cases in at least 10 weeks. The outcome was weekly growth rate defined as the ratio of current cases compared to the previous week. We examined the effects of average time spent outside the home (non-residential mobility) in the prior three weeks using a lognormal regression model accounting for province, season, and mean temperature. We calculated the COVID-19 mobility threshold and gap.ResultsAcross the 44-week study period, a total of 704,294 persons were infected with COVID-19. Non-residential mobility dropped rapidly in the spring and reached a median of 36% (IQR: 31,40) in April 2020. After adjustment, each 5% increase in non-residential mobility was associated with a 9% increase in the COVID-19 weekly growth rate (ratio=1.09, 95%CI: 1.07,1.12). The mobility gap increased through the fall months, which was associated with increasing case growth.InterpretationMobility strongly and consistently predicts weekly case growth, and low levels of mobility are needed to control COVID-19 through winter 2021. Mobility measures from anonymized smartphone data can be used to guide the provincial and regional implementation and loosening of physical distancing measures.

“…du SRAS-CoV-2 5 . Les données de mobilité qui rendent compte de l'activité humaine par un suivi anonymisé des téléphones intelligents pourraient raisonnablement rendre compte des taux de contacts hors domicile; ces données peuvent fournir des renseignements fiables sur les taux de contacts plus rapidement que les enquêtes sur l'emploi du temps et les recherches de contacts [6][7][8] .…”

unclassified

Écart de mobilité : estimation des seuils de mobilité requis pour maîtriser le SRAS-CoV-2 au Canada

Buchan

et al. 2021

CMAJ

e bilan mondial de la maladie à coronavirus 2019 (COVID-19) continue de s'alourdir, malgré la promesse que recèlent les vaccins récemment approuvés. Une recrudescence s'observe dans de nombreux pays de l'hémisphère nord, y compris au Canada, ce qui pourrait alourdir considérablement le fardeau avant que la vaccination soit suffisante pour donner lieu à une immunité collective. Les interventions non pharmacologiques de la santé publique, y compris la distanciation physique, demeurent le principal moyen de maîtriser la COVID-19 à l'échelle des populations 1 . Depuis le début de la deuxième vague, qui a commencé en septembre 2020, des enquêtes ont laissé entendre qu'une majorité de personnes au Canada appuie et respecte les restrictions imposées par les gouvernements 2 , et qu'elles sont nombreuses à approuver un resserrement des mesures pour maîtriser la transmission communautaire du coronavirus du syndrome respiratoire aigu sévère (SRAS-CoV-2), l'agent viral à l'origine de la COVID-19 3 .Le SRAS-CoV-2 se propage principalement lors de contacts étroits avec des personnes porteuses 4 . Comme avec toute maladie infectieuse, le taux de contacts est le principal moteur de la transmission RECHERCHE Écart de mobilité : estimation des seuils de mobilité requis pour maîtriser le SRAS-CoV-2 au Canada