A Canadian drugmaker said its plant-based Covid-19 vaccine showed strong protection against the virus and will soon seek authorisation at home and elsewhere.

Medicago announced that its two-dose vaccine was 71 per cent effective at preventing Covid-19 infection in a large, late-stage study that included several variants, including the Delta variant.

The company's results did not include the emerging omicron variant, which wasn't circulating during the study period, AP reports.

The Quebec City company said it will seek Canadian approval imminently and has also begun the process to file with regulators in the US, UK and other countries. The company said it's also preparing to send its data to the World Health Organisation.