Behavioral changes before lockdown and decreased retail and recreation mobility during lockdown contributed most to controlling COVID-19 in Western countries

  1. Koen Deforche
  2. Jurgen Vercauteren
  3. Viktor Müller
  4. Anne-Mieke Vandamme

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Abstract

Background

The COVID-19 pandemic has prompted a lockdown in many countries to control the exponential spread of the SARS-CoV-2 virus, hereby reducing the time-varying basic reproduction number ( R t ) to below one. Governments are looking for evidence to balance the demand of their citizens to ease some of the restriction, against the fear of a new peak in infections. In this study, we wanted to quantify the relative contribution of mobility restrictions, and that of behavioral changes that occurred already before the lockdowns, on the reduction of transmission during lockdowns in Western countries in early 2020.

Methods

Incidence data of cases and deaths from the first wave of infections for 35 Western countries (32 European, plus Israel, USA and Canada) were analyzed using epidemiological compartment models in a Bayesian framework. Mobility data was used to estimate the timing of changes associated with a lockdown, and was correlated with estimated reductions of R t .

Results

Across all countries, the initial median estimate for R t was 3.6 (95% IQR 2.4–5.2), and it was reduced to 0.78 (95% IQR 0.58–1.01) during lockdown. 48% (18–65%) of the reduction occurred already in the week before lockdown, with lockdown itself causing the remaining drop in transmission. A lower R t during lockdown was independently associated with an increased time spent at home (0.21 per 10% more time, p  < 0.007), and decreased mobility related to retail and recreation (0.07 per 10% less mobility, p  < 0.008).

Conclusions

In a Western population unaware of the risk, SARS-CoV-2 can be highly contagious with a reproduction number R 0  > 5. Our results are consistent with evidence that recreational activities (including restaurant and bar visits) enable super-spreading events. Exiting from lockdown therefore requires continued physical distancing and tight control on this kind of activities.

Article activity feed

  1. Version published to 10.1186/s12889-021-10676-1
  2. Version published to 10.21203/rs.3.rs-65547/v2 on Research Square
  3. Version published to 10.21203/rs.3.rs-65547/v1 on Research Square
  4. ScreenIT

    SciScore for 10.1101/2020.06.20.20136382: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

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    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
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    • No protocol registration statement was detected.

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  5. Version published to 10.1101/2020.06.20.20136382v1 on medRxiv