As some countries proceed to human trials in the race for a COVID-19 vaccine, Canada lags behind with many questions left unanswered by federal officials.

Mexico aims to conduct late-stage clinical trials within months for COVID-19 vaccines in development by Johnson & Johnson, Cansino Biologics Inc and Walvax Biotechnology Co Ltd.

The Ad5-nCoV is one of China's eight vaccine candidates approved for human trials at home and abroad for the respiratory disease caused by the new coronavirus.

The findings land just before researchers at Dalhousie University test the same vaccine in Halifax in the upcoming weeks.