Doctor hand wearing medical gloves in close up view hold a vaccine bottle vial while transferring medication to an injection syringe used for treatment of Covid-19 patients THUNDER BAY -- Monday marks the arrival of walk-in clinics at the Thunder Bay District Health Unit's vaccination sites at the Canadian Lakehead Exhibition Grounds. Under guidance from the province, anyone 12 and older will be able to receive a first or second dose of a COVID-19 vaccine without a pre-booked appointment. To accommodate the added numbers, additional walk-in spots are being put in place and the health unit will use space at both the Coliseum and Heritage buildings.