What the data say about border closures and COVID spread

As countries in Europe rush to close their borders to the United Kingdom to prevent transmission of a new — and potentially more transmissible — variant of SARS-CoV-2, research has estimated the effect of international travel restrictions on COVID-19 spread earlier in the pandemic.

Models have found that strict border closures could have helped limit viral transmission in the pandemic’s early days. But once the virus started spreading in other countries, border closures provided little benefit.

Before the COVID-19 pandemic, most countries had only ever imposed border restrictions on select...