Canada has approved the Covid-19 vaccine developed by American biotech firm Moderna, the health department announced Wednesday, two weeks after authorizing immunizations with the Pfizer/BioNTech shot.

The decision makes Canada the second country to green light the Moderna vaccine, after the US.

"Health Canada... has determined that the Moderna vaccine meets the department's stringent safety, efficacy and quality requirements," it said in a statement.

The authorization is a "critical step," the statement continued.

"The different storage and handling requirements of the Moderna COVID-19 vaccine mean that it can be distributed to isolated and remote communities, including the territories," it added.

The Moderna vaccine can be stored at -20 degrees Celsius (-4 degrees Fahrenheit), much warmer than Pfizer's vaccine which must be kept at -70 degrees Celsius (-94 degrees Fahrenheit), making it easier to distribute.

Prime Minister Justin Trudeau has said previously that Canada is set to receive up to 168,000 doses of Moderna's vaccine before the end of December, part of the guaranteed 40 million it has secured. 

Delivery could begin within 48 hours of the Moderna vaccine's approval, he said earlier this month. 

Canada began vaccinating people in high-risk categories -- including frontline health care workers and residents and staff of long-term care facilities -- on December 14, with its relatively limited supply of the Pfizer-BioNTech vaccine. 

Both the Pfizer and Moderna vaccines use a cutting-edge technology based on mRNA (messenger ribonucleic acid) which makes the human cells they enter express a surface protein of the new coronavirus.

This simulates an infection and trains the immune system to be ready in case it encounters the real virus. 

In total, Canada -- a country of 38 million -- has placed orders or options on more than 400 million doses of vaccine from seven pharmaceutical groups. 

The country will share any excess doses with other countries, Trudeau has said.

Canada plans to vaccinate three million people by the end of the first quarter of 2021. 

The country, where the spread of the virus accelerated as the holiday season approached, on Wednesday had recorded more than 523,000 cases of coronavirus and nearly 14,500 deaths since the start of the pandemic.