Evidence of initial success for China exiting COVID-19 social distancing policy after achieving containment

Abstract

Background: The COVID-19 epidemic was declared a Global Pandemic by WHO on 11 March 2020. By 24 March 2020, over 440,000 cases and almost 20,000 deaths had been reported worldwide. In response to the fast-growing epidemic, which began in the Chinese city of Wuhan, Hubei, China imposed strict social distancing in Wuhan on 23 January 2020 followed closely by similar measures in other provinces. These interventions have impacted economic productivity in China, and the ability of the Chinese economy to resume without restarting the epidemic was not clear. Methods: Using daily reported cases from mainland China and Hong Kong SAR, we estimated transmissibility over time and compared it to daily within-city movement, as a proxy for economic activity. Results: Initially, within-city movement and transmission were very strongly correlated in the five mainland provinces most affected by the epidemic and Beijing. However, that correlation decreased rapidly after the initial sharp fall in transmissibility. In general, towards the end of the study period, the correlation was no longer apparent, despite substantial increases in within-city movement. A similar analysis for Hong Kong shows that intermediate levels of local activity were maintained while avoiding a large outbreak. At the very end of the study period, when China began to experience the re-introduction of a small number of cases from Europe and the United States, there is an apparent up-tick in transmission. Conclusions: Although these results do not preclude future substantial increases in incidence, they suggest that after very intense social distancing (which resulted in containment), China successfully exited its lockdown to some degree. Elsewhere, movement data are being used as proxies for economic activity to assess the impact of interventions. The results presented here illustrate how the eventual decorrelation between transmission and movement is likely a key feature of successful COVID-19 exit strategies.

Modeling COVID-19 scenarios for the United States

“…Altitude was sourced from the National Oceanic and Atmospheric Administration National Centers for Environmental Information Global Land One-km Base Elevation Project ( https://www.ngdc.noaa.gov/mgg/topo/globe.html ) and population data were obtained from WorldPop Population Counts ( https://www.worldpop.org/project/list/ ). These sources are further detailed in the Supplementary Information 44 – 51 . Source data are provided with this paper.…”

Coronavirus Disease 2019 (COVID-19) Transmission in the United States Before Versus After Relaxation of Statewide Social Distancing Measures

“…Little data exist to inform the US exit strategy from its current state of social distancing measures. The city of Wuhan in Hubei Province, China, was the first to enter a regime of strict social distancing (beginning 23 January 2020), but the relaxation of these measures has not resulted in a resurgence of SARS-CoV-2 transmission [ 39 ]. Within 2 months, the Chinese government was able to achieve the milestone of having 5 consecutive days in which there were no new locally transmitted cases in the country [ 40 ].…”

Reduction in mobility and COVID-19 transmission

“…In the face of the threats posed by COVID-19, most countries rapidly implemented strict social distancing policies to suppress transmission (bringing R below 1) and thus avoid overwhelming healthcare capacity 13 . While a convincing reduction in case incidence was observed, at least temporarily, in many countries 14 – 18 , and in some cases a reduction in transmission has been explicitly linked to the reduction in mobility 19 , 20 , many countries are still experiencing continued or resurgence of widespread transmission of SARS-CoV-2 21 , 22 .…”