Transmission dynamics and the effects of non-pharmaceutical interventions in the COVID-19 outbreak resurged in Beijing, China: a descriptive and modelling study

Objective To evaluate epidemiological characteristics and transmission dynamics of COVID-19 outbreak resurged in Beijing and to assess the effects of three non-pharmaceutical interventions. Design Descriptive and modelling study based on surveillance data of COVID-19 in Beijing. Setting Outbreak in Beijing. Participants The database included 335 confirmed cases of COVID-19. Methods To conduct spatiotemporal analyses of the outbreak, we collected individual records on laboratory-confirmed cases of COVID-19 from 11 June 2020 to 5 July 2020 in Beijing, and visitor flow and products transportation data of Xinfadi Wholesale Market. We also built a modified susceptible-exposed-infected-removed model to investigate the effect of interventions deployed in Beijing. Results We found that the staff working in the market (52.2%) and the people around 10 km to this epicentre (72.5%) were most affected, and the population mobility entering-exiting Xinfadi Wholesale Market significantly contributed to the spread of COVID-19 (p=0.021), but goods flow of the market had little impact on the virus spread (p=0.184). The prompt identification of Xinfadi Wholesale Market as the infection source could have avoided a total of 25 708 (95% CI 13 657 to 40 625) cases if unnoticed transmission lasted for a month. Based on the model, we found that active screening on targeted population by nucleic acid testing alone had the most significant effect. Conclusions The non-pharmaceutical interventions deployed in Beijing, including localised lockdown, close-contact tracing and community-based testing, were proved to be effective enough to contain the outbreak. Beijing has achieved an optimal balance between epidemic containment and economic protection.

Automated summary

The study evaluated the epidemiological characteristics and transmission dynamics of the COVID-19 outbreak in Beijing, finding that the population around Xinfadi Wholesale Market and the market staff were most affected by the virus. Prompt identification of the market as the infection source could have significantly reduced the number of cases. Non-pharmaceutical interventions in Beijing, including localized lockdowns and community-based testing, were effective in containing the outbreak while balancing economic protection.