The Royals placed Keller (personal) on the restricted list Thursday.
Keller is one of 10 Royals on the 26-man active roster who won't be eligible for the four-game series in Toronto due to his vaccination status. He'll be formally reinstated from the restricted list for the Royals' first game coming out of the All-Star break July 22 against Tampa Bay. Left-hander Angel Zerpa was called up from Double-A Northwest Arkansas as a replacement pitcher, and he could be an option to start one of the final two games of the series in Toronto if he isn't used out of the bullpen the next two days.