Does city lockdown prevent the spread of COVID-19? New evidence from the synthetic control method

Abstract

Background At 10 a.m. on January 23, 2020 Wuhan, China imposed a 76-day travel lockdown on its 11 million residents in order to stop the spread of COVID-19. This lockdown represented the largest quarantine in the history of public health and provides us with an opportunity to critically examine the relationship between a city lockdown on human mobility and controlling the spread of a viral epidemic, in this case COVID-19. This study aims to assess the causal impact of the Wuhan lockdown on population movement and the increase of newly confirmed COVID-19 cases. Methods Based on the daily panel data from 279 Chinese cities, our research is the first to apply the synthetic control approach to empirically analyze the causal relationship between the Wuhan lockdown of its population mobility and the progression of newly confirmed COVID-19 cases. By using a weighted average of available control cities to reproduce the counterfactual outcome trajectory that the treated city would have experienced in the absence of the lockdown, the synthetic control approach overcomes the sample selection bias and policy endogeneity problems that can arise from previous empirical methods in selecting control units. Results In our example, the lockdown of Wuhan reduced mobility inflow by approximately 60 % and outflow by about 50 %. A significant reduction of new cases was observed within four days of the lockdown. The increase in new cases declined by around 50% during this period. However, the suppression effect became less discernible after this initial period of time. A 2.25-fold surge was found for the increase in new cases on the fifth day following the lockdown, after which it died down rapidly. Conclusions Our study provided urgently needed and reliable causal evidence that city lockdown can be an effective short-term tool in containing and delaying the spread of a viral epidemic. Further, the city lockdown strategy can buy time during which countries can mobilize an effective response in order to better prepare. Therefore, in spite of initial widespread skepticism, lockdowns are likely to be added to the response toolkit used for any future pandemic outbreak.

Analysis of the Complex Network of the Urban Function under the Lockdown of COVID-19: Evidence from Shenzhen in China

“…The results show that tourism and catering industry are influenced more greatly than audio-visual and digital entertainment, and the service functions and the development of facilities should be improved. Yang explored the causal relationship between the incidence of COVID-19 disease and the incidence of new COVID-19 cases in Wuhan of China using panel data from 279 cities [24]. The result shows that lockdown can be an effective short-term tool to contain and slow the spread of the virus.…”

Research on the Efficiency measurement of the Lockdown approach based on the Perspective of GDP

“…Yang (2021) analyzed that when the situation comes with no effective vaccination, city-wide locking down can positively reduce population movement and significantly contain and delay the spread of Covid-19 in the short term [6]. And the authors also concluded that the unprecedented citywide quarantine in human history in Wuhan provided valuable time for the world to prepare for the fight against the pandemic.…”

“…The authors quoted the analysis of Athey and Imbens to evaluate this method, "SCM method is arguably the most important innovation in the policy evaluation literature in the last 15 years. [6]". After the detailed modeling and controlling the bias, the authors showed a fluctuating decreasing downward trend at the point of Wuhan locking down.…”

eCOVID19 – Development of Ontology-based Clinical Decision Support System for COVID-19

“…Also, because of the fear of community spread, people could not travel to hospitals to seek the necessary support. Due to the coronavirus, countries issued lockdown and travel bans [2][3][4][5] to prevent the spread.…”