SARS-CoV-2 transmission across age groups in France and implications for control

Cécile Tran Kiem (1, 2, 3) , Paolo Bosetti (1, 3) , Juliette Paireau (1, 4, 3) , Pascal Crepey (5, 6) , Henrik Salje (1, 3, 7) , Noémie Lefrancq (1, 7, 3) , Arnaud Fontanet (8, 3) , Daniel Benamouzig (9) , Pierre-Yves Boëlle (10) , Jean-Claude Desenclos (4) , Lulla Opatowski (11, 12, 3, 13) , Simon Cauchemez (1, 3)

1 Modélisation mathématique des maladies infectieuses - Mathematical modelling of Infectious Diseases
2 Collège Doctoral
3 UPCité - Université Paris Cité
4 Santé publique France - French National Public Health Agency [Saint-Maurice, France]
5 REPERES - Recherche en Pharmaco-épidémiologie et Recours aux Soins
6 EHESP - École des Hautes Études en Santé Publique [EHESP]
7 CAM - University of Cambridge [UK]
8 Epidémiologie des Maladies Emergentes - Emerging Diseases Epidemiology
9 CSO - Centre de sociologie des organisations (Sciences Po, CNRS)
10 iPLESP - Institut Pierre Louis d'Epidémiologie et de Santé Publique
11 CESP - Centre de recherche en épidémiologie et santé des populations
12 EMAE - Epidémiologie et modélisation de la résistance aux antimicrobiens - Epidemiology and modelling of bacterial escape to antimicrobials
13 UVSQ Santé - Université de Versailles Saint-Quentin-en-Yvelines - UFR Sciences de la santé Simone Veil

The shielding of older individuals has been proposed to limit COVID-19 hospitalizations while relaxing general social distancing in the absence of vaccines. Evaluating such approaches requires a deep understanding of transmission dynamics across ages. Here, we use detailed age-specific case and hospitalization data to model the rebound in the French epidemic in summer 2020, characterize age-specific transmission dynamics and critically evaluate different age-targeted intervention measures in the absence of vaccines. We find that while the rebound started in young adults, it reached individuals aged ≥80 y.o. after 4 weeks, despite substantial contact reductions, indicating substantial transmission flows across ages. We derive the contribution of each age group to transmission. While shielding older individuals reduces mortality, it is insufficient to allow major relaxations of social distancing. When the epidemic remains manageable (R close to 1), targeting those most contributing to transmission is better than shielding at-risk individuals. Pandemic control requires an effort from all age groups.

Mots clés: Computational models; Statistical methods; SARS - CoV-2; Epidemiology

Domaines: Sciences du Vivant [q-bio]

Cécile Tran Kiem, Paolo Bosetti, Juliette Paireau, Pascal Crepey, Henrik Salje, et al.. SARS-CoV-2 transmission across age groups in France and implications for control. Nature Communications, 2021, 12 (1), pp.6895. ⟨10.1038/s41467-021-27163-1⟩. ⟨hal-03468461v3⟩