Canada's 'residual positives' exemption lets hundreds fly home after recovering from COVID A mechanism for returning travellers who haven't gotten clean negative PCR results — because of the lingering effects of recovering from COVID-19 — has allowed 350 people who once had the illness to return to Canada. Social Sharing More than 300 travellers have been able to return to Canada despite lingering virus and positive PCR tests Posted: May 21, 2021 12:16 PM ET | Last Updated: May 21 A COVID-19 screening centre is pictured at Vancouver International Airport in Richmond, B.C. Friday, February 19, 2021.(Jonathan Hayward/The Canadian Press)