Background
Prior to Wuhan quarantine in 2020, chunyun, the largest population mobility on this planet, had begun. We quantify impacts of Wuhan quarantine on COVID-19 spread during chunyun at a nationwide and a local level.
Methods
During the period of January 1 to February 9, 2020, a total of 40,278 confirmed COVID-19 cases from 319 municipalities in mainland China were modelled with the cross-coupled meta-population methods using between-city Baidu migration index. Four scenarios of geographic spread of COVID-19 included the presence of both chunyun and quarantine (baseline); quarantine without chunyun (scenario 1); chunyun without quarantine (scenario 2); and the absence of both chunyun and quarantine (scenario 3).
Results
Compared with the baseline, scenario 1 resulted in 3.84% less cases by February 9 while scenario 2 and 3 resulted in 20.22% and 32.46% more cases by February 9. Investigation of geographic distribution of cases revealed that chunyun facilitated the COVID-19 spread in most but not all cities, and effectiveness of city quarantine was offset by chunyun. Impacts of quarantine of Wuhan during chunyun on the COVID-19 spread demonstrate geographical heterogeneity.
Conclusion
Our result strongly supports the travel restriction as one of the effective emergency responses and highlight the importance of developing area-specific countermeasures.