Assessment and prediction of the oversea imported risk of COVID-19 in Shanghai

ObjectiveTo determine the association between global epidemic of COVID-19 and local situation of imported cases from abroad to Shanghai, and then to predict the risk of imported COVID-19 epidemic from December 2020 through March 2021.

MethodsA retrospective analysis on the imported COVID-19 cases from abroad to Shanghai was conducted. The correlation between global and country-specific confirmed COVID-19 cases(weekly confirmed cases per 100 000 population)and imported cases(weekly reported)in Shanghai was determined. Compared to the risk in November 2020, country-specific risk of imported cases to Shanghai was assessed to calculate the possible number of imported case in the near future using SEIR model.

ResultsThe number of imported case of COVID-19 from abroad to Shanghai increased along with the global epidemic, with several peaks accordingly. However, the imported cases did not accumulate, as potential epidemic has been always effectively contained through timely implementation of prevention and control measures. The number of weekly imported cases in Shanghai was significantly correlated with the number of global weekly confirmed cases per 100 000 population(r_Spearman = 0.349, P = 0.029), and also correlated with weekly reported cases in certain countries(P < 0.05), such as the UK and France. Using the number of imported cases from abroad to Shanghai in November as baseline, the estimated monthly number of imported cases in Shanghai might increase in the following four months.

ConclusionThe risk of imported COVID-19 cases from abroad to Shanghai may increase in the near future. Prediction of imported case would provide scientific evidence for optimizing prevention and control measures and reserving medical resources for the imported epidemic.