The Canadian border remains closed to unvaccinated visitors –, and that includes unvaccinated baseball players. This will likely cause some issues when the baseball season begins.
The Red Sox do not play in Toronto until April 25, when they have a four-game series. At that time, assuming Canada's policy does not change, any unvaccinated players will be placed on the restricted list and will not accompany the team. They will not be paid and will not accrue service time for those games, according to the new CBA.
Jennings describes the Red Sox (one of seven teams who did not reach MLB's 85% vaccination threshold last season) as "among the least-vaccinated teams in the majors last year".