Epidemiological characteristics of imported cases of COVID-19 from Association of Southeast Asian Nations countries to China

  Objective  To understand the epidemiological characteristics of imported coronavirus disease 2019 (COVID-19) cases from Association of Southeast Asian Nations (ASEAN) countries in China from January 1, 2020 to February 28, 2021, and provide evidence for the improvement of China's strategy of COVID-19 control towards travelers from ASEAN countries.

  Methods  Data were obtained from the National Infectious Disease Reporting Information Management System of China Disease Prevention and Control Information System and the World Health Organization (WHO) website. The socio-demographic characteristics, clinical types, temporal, spatial and population distributions of the imported COVID-19 cases from ASEAN countries in China were analyzed by descriptive epidemiological methods.

  Results  From January 2020 to February 2021, a total 1 585 imported COVID-19 cases from ASEAN countries were reported in China, accounting for 18.51% of total imported cases in China. The sex ratio of the imported COVID-19 cases was 3.95:1. The average age of the cases was (35.21±11.09) years. Workers, house workers and people engaged in business service were the top 3 populations affected, with the proportions of 21.26%, 13.56% and 12.93%, respectively. The majority of imported cases were asymptomatic (921 cases, 58.11%), the others were pneumonia cases (407 cases, 25.68%) and mild cases (256 cases, 16.15%). The incidence peak of imported COVID-19 cases occurred during August - October, 2020 (940 cases, 59.46%). The main source countries were the Philippines (775 cases, 48.90%), Indonesia (301 cases, 18.99%) and Singapore (279 cases, 17.60%). The cases were distributed in 24 provinces and municipalities. Guangdong (420 cases, 26.50%), Fujian (255 cases, 16.09%) and Shanghai (137 cases, 8.64%) were the top 3 areas. There were 83.85% of the imported cases diagnosed within three days after onset.

  Conclusion  The majority of the imported COVID-19 cases in China from ASEAN countries were male young adults with asymptomatic infections. Given that the spread risk of COVID-19 from ASEAN countries might exist for a long time, all the entry points of China should continue the current strict control strategy to prevent community spread caused by imported COVID-19 cases.