The effect of the synchronized multi-dimensional policies on imported COVID-19 curtailment in China

Abstract

As countries are lifting restrictions and resuming international travels, the rising risk of COVID-19 importation remains concerning, given that the SARS-CoV-2 virus could be transmitted unintentionally through the global transportation network. To explore and assess the effective strategies for curtailing the epidemic risk from international importation nationwide, we evaluated "the joint prevention and control" mechanism, which made up of 19 containment policies, on how it impacted the change of medical observation and detection time from border arrival to laboratory confirmation of COVID-19 in its burst in China. Based on 1,314 epidemiological-survey cases from February 29 to May 25, 2020, we found that the synchronized approach of implementing multi-dimensional interventional policies, such as a centralized quarantine and nucleic acid testing (NAT), flight service adjustment and border closure, effectively facilitate early identification of infected case. Specifically, the implementation of the international flight service reduction was found to be associated with a reduction of the mean intervals of diagnosis from arrival to lab-confirmation by 0.44 days maximally, and the border closure was associated with a reduction of the diagnosis interval of imported cases by 0.69 days, from arrival to laboratory confirmation. The study suggests that a timely and synchronized implementation of multi-dimensional policies is compelling in preventing domestic spreading from importation.

Fig 1. Multi-dimensional interventional policies and the distributions of imported confirmed cases and their diagnosis intervals.

The figure illustrates the evolution of abrupt upsurge of COVID-19 imported cases and the progressive multi-dimensional policies implemented in China from February 29 to May 25, 2020 (and no imported case was reported during May 26–31, 2020).

Fig 2. Spatial distribution of imported COVID-19 cases during Feb 29 –May 31, 2020.

Note: Among the 1,314 cases we collected, 533 observations are from Heilongjiang province, 174 cases from Beijing, 66 from Tianjin, 317 from Shanghai, 77 from Xi’an, 12 from Yunnan province and 135 from Guangzhou of Guangdong province.

Fig 3. Inbound travel routes of 1,237 imported cases during February 29 –May 31, 2020.

Note: Based on the sample data, 189 cases were reported traveling from Europe and the U. S. in the early outbreaks of COVID-19, mainly from London (119), New York (42), and Paris (28). Along with the reduction of the international flights started on March 29 and onward, most imported cases (679) were reported that either originated from or transferred via Russia.

Fig 4. Temporal change of imported case by countries during February 29 –May 31, 2020.

Note: The summary was based on the date of arrival. The number of importations from Russia is relatively concentrated and large, while the ones from the severely affected countries such as the U.K., the U.S. and France lasted longer.

Fig 5. Characteristics of the imported COVID-19 cases.

(A) reveals the distributions of the periods from the port of entry to testing positivity and lab confirmation, respectively, based on the sample data. The mean interval from arrival to test positivity and to a lab confirmation of the four groups of cases are shown in the parenthesis. (B) illustrates the time interval from entry to a case confirmation and the sample distribution based on the assumption of different incubation periods. (C) reflects the estimated temporal distribution of possible infection dates of the samples, based on the date of departure, date of confirmation, and assumptions of different incubation periods. (D) shows the correlation between the average time of confirmation of cases and the epidemic risk of different countries.