Restrictions on flights in and out of China wouldn’t have prevented the novel coronavirus from circling the globe, a new model shows. Even if the amount of international travel in and out of China had been cut by 90 percent after February 1st, the trajectory of the epidemic would not have changed significantly — not without other efforts made to stop the spread of infection, like the isolation of people who were sick.
The model, published in the journal Science, was built using transportation data and information on the dynamics of COVID-19, the disease caused by the novel coronavirus. The authors generated a range of possible scenarios for the movement of the disease through China and around the world.
Officials quarantined the city of Wuhan, China, where the virus originated, at the end of January. The model found that shutting down the Wuhan airport would only delay spread of the epidemic through mainland China by under a week. By January 23rd, it showed the virus would have been brought to several places around the country. That projection matches World Health Organization (WHO) data on cases of COVID-19 in China.
Travel restrictions in and out of Wuhan slowed the number of cases imported from China into other countries by two to three weeks, according to the model. But there were already enough cases outside of Wuhan by that point that stopping international spread was impossible — the virus could travel from Shanghai, Beijing, Shenzhen, and other cities.
The model’s conclusions were echoed by experts at the WHO. “Measures on movement restriction have delayed the dissemination of the outbreak two or three days within China and a few weeks outside China,” Sylvie Briand, director of infectious hazard management at the WHO, said in a press conference.
The WHO originally said that countries should not restrict travel in response to the novel virus, and experts questioned the wisdom of locking down cities. But even though it did not stop the epidemic from jumping outside of China, the delay bought other countries some time to prepare. The cost to people living in Wuhan, though, has been high — residents and health care workers have been living and working under a psychologically and physically taxing lockdown for weeks.
Now that the virus is present around the world, additional or continued travel restrictions are likely to have a limited impact on the epidemic, the researchers wrote. Policies that reduce the spread of disease within communities, like early detection and isolation of cases, will be the best way to fight the outbreaks, they concluded.