A vial of the measles, mumps, and rubella virus (MMR) vaccine is pictured at the International Community Health Services clinic in Seattle, Washington, U.S., March 20, 2019.

A national shortage of measles vaccines will continue for at least another month, which means most people born before 1970 won't be able to follow public health advice and get a shot before travel outside Canada — unless they cross the border to get the shot.