Vaccine efficacy refers to the percentage reduction of disease in a vaccinated group of people compared to an unvaccinated group, under ideal conditions. Pfizer-BioNtech and Moderna both have been determined by Health Canada to have efficacy rates of around 95 per cent. AstraZeneca-Oxford has an efficacy rate of 62 per cent while Johnson & Johnson has an efficacy rate of 66.9 per cent. Detroit turned down Johnson & JohnsonIn Detroit, Mayor Mike Duggan last week turned down 6,200 doses of the Johnson & Johnson vaccine, saying he favoured shots from Pfizer and Moderna for now. Johnson & Johnson and AstraZeneca, meanwhile, had their trials later when more transmissible coronavirus variants were spreading at a rapid pace.

Source: CBC News March 09, 2021 09:00 UTC