OTTAWA—Prime Minister Justin Trudeau says Canada has signed a tentative agreement for Novavax to produce millions of doses of its COVID-19 vaccine in Canada once it’s approved for use here. The U.S. company is still doing clinical trials of its vaccine but if Health Canada approves it, a new National Research Council facility in Montreal will begin pumping out Novavax doses when the building is finished later this year. It would be the first COVID-19 vaccine to be produced domestically. Canada is currently at the mercy of foreign governments, which could at any time slam the doors shut to vaccine exports until their own people are vaccinated. That risk becomes ever more real this week as Europe’s new export controls on vaccines take hold, putting at risk Canada’s entire supply of COVID-19 vaccines. Trudeau also says additional vaccines could be produced in Saskatchewan and Vancouver, but there are no deals …