Canada's first 300,000 doses of the Johnson & Johnson COVID-19 vaccine are arriving today, a federal official tells The Canadian Press.

The official, granted anonymity to discuss matters not made public yet, said that where the doses are coming from is not being disclosed because the government needs to ``protect this new vaccine supply chain.''

J&J has struggled with production problems and has been able to deliver very few doses, even in the United States.

Canada purchased 10 million doses, and has the option to buy 28 million more.

The doses are expected to be distributed to provinces next week.

The National Advisory Committee on Immunization has not yet provided guidance on how the vaccine should be used alongside the other three in use already.

This week's delivery of just over one million doses from Pfizer-BioNTech is already in Canada.

A delayed shipment of about 650,000 doses from Moderna is also en route to Canada now.

650,000 doses of the Moderna vaccine arrive in Canada

Canada Border Services Agency says it has processed the arrival of 650,000 doses of the Moderna vaccine at Toronto's Pearson Airport.

The shipment was delayed from last week, and only half of what was initially expected as the company continues to face some issues with production in Europe.

The doses will first go to an Innomar Strategies warehouse, the logistics company contracted by Canada to receive all vaccines but Pfizer-BioNTech.

Innomar will repackage the doses and then redistribute them to provincial and territorial governments within the next few days.