The largest unions in the United States and Canada are questioning the fairness of a vote set for General Motors Co.'s truck plant in Mexico Feb. 1 and 2.

The automaker had originally planned to bar unvaccinated staff from Canadian sites Dec. 17 after announcing the vaccine requirement in mid-October. It's been moved to Dec. 31.

Unifor is fighting back against the Detroit Three's vaccine mandate, but the union requires its 425 employees to be fully vaccinated against COVID-19 before they come into work, a policy that began Nov. 1.

Two auto parts plant closures in Ingersoll, Ont., and hundreds of job losses at other suppliers of General Motors’ CAMI Assembly plant could be just the beginning as Canadian vehicle plants transition to building electrified products.