Foreigners wishing to enter the United States via a land border — no matter the reason for their trip — will need to be vaccinated against Covid-19 starting Saturday, the Department of Homeland Security said.

The US, which had largely closed its borders to the outside world at the start of the pandemic, reopened to most travellers in November, on the condition that they were vaccinated.

Foreigners arriving via land or by ferry from Mexico and Canada had been exempt for “essential” trips, especially for professional reasons.

But that exemption will expire on Saturday, particularly affecting commuters who live and work on opposite sides of either the Canadian-US or Mexican-US borders.