Lockdown impact on age-specific contact patterns and behaviours, France, April 2020

Paolo Bosetti (1, 2) , Bich-Tram Huynh (3, 4) , Armiya Youssouf Abdou (3, 4) , Marie Sanchez (5) , Catherine Eisenhauer (1, 2) , Noémie Courtejoie (6) , Jérôme Accardo (7) , Henrik Salje (1, 2, 8) , Didier Guillemot (3, 4) , Mathieu Moslonka-Lefebvre (9) , Pierre-Yves Boëlle (10) , Guillaume Béraud (11) , Simon Cauchemez (1, 2) , Lulla Opatowski (3, 4)

1 Modélisation mathématique des maladies infectieuses - Mathematical modelling of Infectious Diseases
2 UPCité - Université Paris Cité
3 EMAE - Epidémiologie et modélisation de la résistance aux antimicrobiens - Epidemiology and modelling of bacterial escape to antimicrobials
4 CESP - Centre de recherche en épidémiologie et santé des populations
5 Data Management (Plate-forme) - Data Management Core Facility (Platform)
6 DREES - Direction de la recherche, des études, de l’évaluation et des statistiques [Paris]
7 Institut national de la statistique et des études économiques (INSEE)
8 CAM - University of Cambridge [UK]
9 DataCovid
10 iPLESP - Institut Pierre Louis d'Epidémiologie et de Santé Publique
11 CHU de Poitiers - Centre hospitalier universitaire de Poitiers = Poitiers University Hospital

Background Many countries implemented national lockdowns to contain the rapid spread of SARS-CoV-2 and avoid overburdening healthcare capacity. Aim We aimed to quantify how the French lockdown impacted population mixing, contact patterns and behaviours. Methods We conducted an online survey using convenience sampling and collected information from participants aged 18 years and older between 10 April and 28 April 2020. Result Among the 42,036 survey participants, 72% normally worked outside their home, and of these, 68% changed to telework during lockdown and 17% reported being unemployed during lockdown. A decrease in public transport use was reported from 37% to 2%. Participants reported increased frequency of hand washing and changes in greeting behaviour. Wearing masks in public was generally limited. A total of 138,934 contacts were reported, with an average of 3.3 contacts per individual per day; 1.7 in the participants aged 65 years and older compared with 3.6 for younger age groups. This represented a 70% reduction compared with previous surveys, consistent with SARS-CoV2 transmission reduction measured during the lockdown. For those who maintained a professional activity outside home, the frequency of contacts at work dropped by 79%. Conclusion The lockdown affected the population's behaviour, work, risk perception and contact patterns. The frequency and heterogeneity of contacts, both of which are critical factors in determining how viruses spread, were affected. Such surveys are essential to evaluate the impact of lockdowns more accurately and anticipate epidemic dynamics in these conditions.

Domaines: Sciences du Vivant [q-bio]

Paolo Bosetti, Bich-Tram Huynh, Armiya Youssouf Abdou, Marie Sanchez, Catherine Eisenhauer, et al.. Lockdown impact on age-specific contact patterns and behaviours, France, April 2020. Eurosurveillance, 2021, 26 (48), pp.2001636. ⟨10.2807/1560-7917.ES.2021.26.48.2001636⟩. ⟨pasteur-03464765⟩