Changes in contact patterns shape the dynamics of the COVID-19 outbreak in China

Corresponding authors: Marco Ajelli and Hongjie Yu

Affiliations: Bruno Kessler Foundation, Italy; Fudan University, China

Publication date: this article was published on June 26, 2020

DOI: 10.1126/science.abb8001

Highlights

In this article, the researchers analyzed contact survey data for Wuhan and Shanghai before and during the outbreak and contact-tracing information from Hunan province. Daily contacts were reduced seven- to eightfold during the COVID-19 social distancing period, with most interactions restricted to the household. They found that children less than 14 years of age were less susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than adults 15 to 64 years of age (odds ratio 0.34, 95% confidence interval 0.24 to 0.49), whereas individuals more than 65 years of age were more susceptible to infection (odds ratio 1.47, 95% confidence interval 1.12 to 1.92). Based on those data, they built a transmission model to study the impact of social distancing and school closure on transmission. They found that social distancing alone, as implemented in China during the outbreak, is sufficient to control COVID-19. Although proactive school closures cannot interrupt transmission on their own, they can reduce peak incidence by 40 to 60% and delay the epidemic.

Nomination Reasons

The publication presented the results of the first study that quantifies the effects of the lockdown on the intensity of social interactions and provides evidence of the reduced children's susceptibility to SARS-CoV-2 infection. This work has been the first landmark in understanding the magnitude of the link between age-related SARS-CoV-2 epidemiology and changes in human contact behavior with the dynamics of infection spread. Despite the estimated lower susceptibility of children, this study warns that, due to the large number of school contacts, the transmission in schools may significantly contribute to the surge of infections in the population as a whole. Thus, this publication explains why a relatively low number of children was reported when physical distancing measures were in place and provides actionable information for the policy-makers.

The paper was picked up by 200+ media outlets worldwide and has been ranked in the top 5% of all research outputs ever tracked by Altmetric (#312 out of 15+ million scientific outputs).

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