The Effect of International Travel on the Spread of COVID-19 in the U.S.

We examine the relationship between incoming international passengers and COVID-19 case or death counts during the first wave of the pandemic in the U.S. We find passengers from Italy, but not China, were an important source of exposure, and thus increased the early spread of COVID-19 in the U.S. These results suggest stopping travel from Europe earlier likely would have had greater impact on reducing the spread of the virus in the US, compared to the earlier ban on travel from China. Further, banning travel from pandemic hotspots may be smart policy, depending on the specific characteristics of the virus.