A new holistic view of global human mobility to better coordinate international movement restriction would benefit governments and policy makers and is the key to understanding the virus spread pattern in the global network of the COVID-19 pandemic.

It could also tackle the limitations inherent in restricting travel only to hotspot areas - a practice akin to “shutting the front door while leaving the back door open”.

This is the outcome of research undertaken at Xi'an Jiaotong-Liverpool University and Fudan University which analysed international travel movement involving more than half a million flights, across six continents between January and April this year, during the critical period of the pandemic spreading across the world.

XJTLU researcher, Dr Lixian Qian, of the University's International Business School Suzhou, said that a global network-based analysis of the spread of the virus between countries would enable policy-makers to better understand the holistic pattern of the virus’ spread across the globe with the introduction of international travel restrictions targeting different countries at different time points, which could lead to the development of more effective worldwide-coordinated measures to combat COVID-19.

“Although countries worldwide have gradually restricted non-essential international travel across countries, particularly those from high-transmission areas, it does not seem to have had the desired effect of stopping the spread of the novel coronavirus (COVID-19),” Dr Qian says.

“Taking the United States as an example, before its restriction for international travelers to enter, the number of new cases in the US was found to be more correlated with the epidemics in three countries. However, after the US gradually banned the entry of foreigners, its daily increment of COVID-19 infections is strongly correlated with seven other countries, mainly from Europe.

“A similar pattern is also found in South Africa, Switzerland, the Netherlands and Brazil, where the gradual restriction of international human mobility did not reduce the correlation between their domestic growths of COVID-19 infections and the international pandemic.

“Overall results of our data analysis indicate that the spread of COVID-19 worldwide has revealed clear associations between international human mobility and focal countries’ epidemic situations over a three-month period, where countries might be influencing and influenced by different countries through various pathways in the network.”

This research includes an association figure of the COVID-19 pandemic among 22 countries in six continents where the association between international movement and countries’ new infections are illustrated:

Fellow researcher Professor Jian-Qiang Hu from the School of Management at Fudan University said that while restricting non-essential international travel between countries is a critical strategy to fight against epidemic outbreaks, given the unprecedented nature of the current pandemic, a lot could be learnt regarding more effective measures to implement this strategy.

“Policymakers might focus only on the hotspot areas with a high transmission rate (which is not wrong) but overlook the pathway effect beyond the epidemic areas in the global network,” Hu says.

“Unfortunately, over the past three months, we have observed such a narrow perspective repeatedly occurring in many countries, focusing only on cutting off hotspot outbreak areas.”

The narrow perspective can relate to the analogy of shutting the “front door” to the pandemic arriving from one country whilst leaving the “back door” open for it to arrive from others.

The research references New York Governor Andrew Cuomo’s comments concerning the US imposing a China travel ban (the front door) but at time when the virus had already left China and could reach the US through human movement and arrivals from other countries.

Dr Qian says that a holistic approach requires governments to adopt a global perspective of understanding and paying greater regard to the dynamic spread of the pandemic, instead of the more piecemeal country-by-country approach to international travel bans that have been introduced at different times.

“Policymakers in every country should keep abreast of population movements between countries and, through scientifically rigorous analysis, foresee the pattern of epidemic transmission in the network,” Dr Qian says

“Accordingly, they should dynamically adjust the corresponding international restriction strategy promptly. It cannot be simply assumed that the international travel ban from high-risk areas will be sufficient to control the epidemic once and for all - while ignoring the dynamic spread of the epidemic in the global network.”

Professor Hu adds that is also important to coordinate the international travel restriction and the internal movement control within each country.

“A number of countries have implemented the lock-down policies in COVID-19 pandemic, but it seems that China and South Korea demonstrated the most effective in controlling the internal transmission, which might be related with how strict the internal movement policy was executed.

“Our research has also analyzed the effectiveness of internal movement policies in different countries.”

The research team also includes Professor Cheng Zhang from the School of Management at Fudan University. The researchers are now developing a simulation model based on this work to help to predict possible outcomes of different restriction policies and aid policymakers to make more effective decisions.

The research paper can be accessed at medRxiv.

By Will Venn

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