Characteristics of COVID-2019 in areas epidemic from imported cases

Objectives The outbreak of the 2019 novel coronaviruses disease (COVID-2019) in areas with epidemics due to imported cases is a cause of concern in China; however, few studies have reported on the prevalence of COVID-19 in these areas. Methods The number of diagnosed cases in Fujian Province was collected, and the time distribution of these cases was analyzed. Results The results showed that the COVID-19 prevalence in areas with epidemics due to imported cases could be divided into two stages. The first stage was an outbreak dominated by imported cases, with the data showing an obviously skewed distribution. The second stage was dominated by nonimported cases with sporadic and low-level fluctuations. Moreover, the data demonstrated that the ratio of unexplained infections to nonimported cases was increasing. Conclusions A two-stage outbreak in areas with epidemics due to imported cases, effective control of the source of infection and blocking of the transmission route can significantly minimize the peak height in the first stage and the spread of the epidemic in the second stage. Control of the epidemic in the second stage requires prevention and control of the aggregation of cases caused by unexplained infections.