The Boston Red Sox will be without at least one member of their starting rotation when they travel north of the border next week.

Tanner Houck revealed to the Boston Globe on Sunday that he's currently unvaccinated against COVID-19, meaning that under Canada's current guidelines, he'll be ineligible to travel to or pitch against the Toronto Blue Jays when the Red Sox head to the Rogers Centre for a four-game series from April 25-28.

"I think it’s a personal choice for everyone whether they get it or not," Houck told Julian McWilliams of the Globe.

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Houck was scheduled to start the second game of the series next Tuesday. Instead, Boston will have to either shuffle its starting rotation or go with a bullpen day against the Blue Jays. The Red Sox are also scheduled to play in Toronto from June 27-29 and Sept. 30-Oct. 2 in the regular season.

Chris Sale, who's currently on the injured list due to a rib injury and not expected to return until at least June, had also said he's unvaccinated against COVID-19 in spring training. If both Sale and Houck were to remain unvaccinated and Canada's guidelines remain in place, 40 percent of Boston's starting rotation at full strength would be ineligible to pitch against the Blue Jays in Toronto this season.

Through two starts in 2022, the 25-year-old Houck is 1-0 with a 3.00 earned run average over nine innings pitched with six walks and seven strikeouts.