The Canada-U.S. border will close to all but essential travel midnight Friday, Prime Minister Justin Trudeau announced.

The move to seal off the undefended, shared border of 5,525 miles is a bid to slow the spread of the coronavirus.

Traffic will be limited to essential goods like food and medical supplies that flow back and forth between the two countries. About five million commercial trucks go cross-border annually carrying about CAN$247 billion in goods.

Irregular migrants will now be stopped and sent back, rather than taking them in and isolating them, he said.

Trudeau also outlined other steps

Read more: Canada-US border closes at Friday midnight: Trudeau