Earlier this week, many were shocked by news of Italy imposing a country-wide lockdown. All public gatherings are banned, including sports events, and people entering or leaving the country will need a good reason to do so. Some have claimed these measures are extreme. But before Italy’s country-wide restrictions, the city of Wuhan, China — the epicenter of the novel coronavirus pandemic — was placed under lockdown in late January. A new study suggests that this radical measure curbed the spread of infection outside mainland China by 80%.
The international team of researchers published their findings in the journal Science. According to the study’s conclusions, when the travel restrictions were imposed in Wuhan, a large number of people exposed to the virus had already been traveling internationally without being detected, spreading the virus that causes COVID-19 to other cities in mainland China. Nevertheless, these travel restrictions delayed the domestic spread of infection by 3-5 days.
In late January, the cities of Shanghai (28.1%), Beijing (14%), and Shenzhen (12.8%) were among the top five ranked cities in terms of case importations. However, case importations fell by around 77% after international flights to and from China were halted.
The risk of importation declined until mid-February, at which point it started rising again after countries like Japan, Thailand, South Korea, Taiwan, and the US. started to import cases of their own through international travelers.
In order to forecast disease transmission under various scenarios, the researchers employed a global disease transmission model known as the Global Epidemic and Mobility Model (GLEAM).
As of March 12th, there are over 127,000 global confirmed cases of COVID-19 in more than 110 countries, which have resulted in 4,718 deaths. After mainland China, Italy is the most affected country with over 12,000 cases, followed by Iran and South Korea.
The authors of the study conclude that although travel restrictions are important for curbing case importation, now that the outbreak has spread globally, such restrictions will only have a moderate effect.
Going forward, the greatest benefits of mitigating the COVID-19 epidemic in each country will come from behavioral changes (frequent hand washing, self-isolation, etc.) and sound public health intervention. Coupled with travel restrictions, these measures can result in a 25% or 50% reduction in the rate of transmission, the authors concluded.