Publications - October 2020

Preprint and peer-reviewed publications from RECOVER’s studies

Evaluating the effect of demographic factors, socioeconomic factors, and risk aversion on mobility during the COVID-19 epidemic in France under lockdown: a population-based study

On March 17, 2020, French authorities implemented a nationwide lockdown to respond to the COVID-19 epidemic and curb the surge of patients requiring critical care. Assessing the effect of lockdown on individual displacements is essential to quantify achievable mobility reductions and identify the factors driving the changes in social dynamics that affected viral diffusion. We aimed to use mobile phone data to study how mobility in France changed before and during lockdown, breaking down our findings by trip distance, user age and residency, and time of day, and analysing regional data and spatial heterogeneities.

Lockdown was effective in reducing population mobility across scales. Caution should be taken in the timing of policy announcements and implementation, because anomalous mobility followed policy announcements, which might act as seeding events. Conversely, risk aversion might be beneficial in further decreasing mobility in highly affected regions. We also identified socioeconomic and demographic constraints to the efficacy of restrictions. The unveiled links between geography, demography, and timing of the response to mobility restrictions might help to design interventions that minimise invasiveness while contributing to the current epidemic response.

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Underdetection of COVID-19 cases in France in the exit phase following lockdown

A novel testing policy was implemented in May in France to systematically screen potential COVID-19 infections and suppress local outbreaks while lifting lockdown restrictions.

Our findings identify critical needs of improvement to increase case ascertainment in France and the performance of the response system to monitor and control COVID-19 epidemic. Substantially more aggressive and efficient testing targeting COVID-19 suspect cases needs to be achieved to act as a pandemic-fighting tool. Associated logistical needs should not be underestimated. These elements should be considered in light of the increase of cases currently observed in France and in other countries in Europe with similar response systems.

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From more testing to smart testing: data-guided SARS-CoV-2 testing choices

We present an in-depth analysis of data from drive through testing stations using rapid antigen detection tests (RDTs), RT-PCR and virus culture, to assess the ability of RDTs to detect infectious cases. We show that the detection limits of five commercially available RDTs differ considerably, impacting the translation into the detection of infectious cases. We recommend careful fit-for-purpose testing before implementation of antigen RDTs in routine testing algorithms as part of the COVID-19 response.

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