Transmissibility of coronavirus disease 2019 (COVID-19) in Chinese cities with different transmission dynamics of imported cases

Abstract

Background: Monitoring the time-varying reproduction number (Rt) of the disease is useful in determining whether there is sustained transmission in a population. In this study, we examined Rt of COVID-19 and compared its transmissibility between different intervention periods in Hangzhou and Shenzhen. Methods: Daily aggregated counts of confirmed imported and local cases between January 1, 2020 and March 13, 2020 were analysed. A likelihood function was constructed to estimate Rt, accounting for imported cases. Results: Although Hangzhou had fewer number of cases than Shenzhen, Shenzhen had higher proportion of imported cases than Hangzhou (83% vs 29%). Since the epidemic of COVID-19 in Shenzhen was dominated by imported cases, Rt was kept below unity through time. On the contrary, Rt was greater than unity in Hangzhou from 16 January to 7 February due to the surge in local cases. Credits to the Wuhan lockdown and outbreak response measures following the local lockdown, Rt decreased steadily and dropped below unity in mid-February. Conclusion: The lockdown measures and local outbreak responses helped reduce the potential of local transmission in Hangzhou and Shenzhen. Meanwhile, cities with similar epidemic trend could have different transmission dynamics given the variation in imported cases.

Synchronized travel restrictions across cities can be effective in COVID-19 control

“…We assume, after the Wuhan lockdown, local travel restrictions in cities outside Hubei contributed to the epidemic control by influencing population mobility 10,16 . Data for three mobility patterns, except the population outflow from Wuhan, in two scenarios were obtained under assumptions.…”

“…Although Wuhan, the capital city of Hubei Province, suspended all inflow and outflow public transport from 10:00 a.m. on 23 January 2020, about 5 million people had already left Wuhan before the quarantine 14 . Studies show that while the Wuhan lockdown greatly slowed the spread of COVID-19 6–10 , the population emigration figure from Wuhan highly correlated to the imported cases in other cities in China 8,11–13,15–18 .…”

Caregivers’ perceived changes in engaged time with preschool-aged children during COVID-19: Familial correlates and relations to children's learning behavior and emotional distress

“…Second, Wuhan was hit the hardest by the pandemic and had the largest number of confirmed COVID-19 cases and deaths among all cities in China (50,340 confirmed cases and 3,869 deaths as of 31 May 2020; Hubei Health Commission, 2020 ). Third, Wuhan imposed one of the toughest lockdowns in the world ( Chong et al., 2020 ). On 23 January 2020, the central government of China instituted a complete city lockdown in Wuhan, suspended all public transport, and prohibited residents of Wuhan from leaving the city ( Chong et al., 2020 ).…”

“…Third, Wuhan imposed one of the toughest lockdowns in the world ( Chong et al., 2020 ). On 23 January 2020, the central government of China instituted a complete city lockdown in Wuhan, suspended all public transport, and prohibited residents of Wuhan from leaving the city ( Chong et al., 2020 ). Although at first people were allowed out, from mid-February, almost all residents were prohibited from leaving their residential communities and all non-essential businesses were shut down ( Chong et al., 2020 ).…”

“…On 23 January 2020, the central government of China instituted a complete city lockdown in Wuhan, suspended all public transport, and prohibited residents of Wuhan from leaving the city ( Chong et al., 2020 ). Although at first people were allowed out, from mid-February, almost all residents were prohibited from leaving their residential communities and all non-essential businesses were shut down ( Chong et al., 2020 ). Consequently, caregivers in Wuhan might have had a unique pattern in their allocation of engaged time with their children during the pandemic.…”