CALGARY -- Health-care workers in Alberta began receiving the first doses of the Pfizer-BioNTech COVID-19 vaccine Tuesday afternoon, said Premier Jason Kenney.

The first immunizations took place about 4 p.m. at hospitals in both Edmonton and Calgary. The two cities have the province's highest number of active cases of the virus.

The announcement comes after 3,900 doses were delivered Monday evening via a UPS plane at the Calgary International Airport. 

Kenney called the arrival of the vaccine a "game changing" moment in the fight against COVID-19. 

Another 25,350 doses are expected to arrive next week as the province hopes to immunize 29,000 health-care workers by the end of the year. 

The Pfizer-BioNTech vaccine requires two separate doses to be taken within three weeks of each other. 

The 29,000 doses will act as first doses for all health-care workers until more arrive, according to Health Minister Tyler Shandro. 

"We don't have to hold back any of that portion for the second dose," he said. "We are going to give the first dose of vaccine to 29,000 health-care professionals by the end of December."

Those eligible for the vaccine include ICU doctors and nurses, respiratory therapists, and some workers in long-term or acute care homes.

The province also expects to start using the Moderna COVID-19 vaccine in early January, pending approval from Health Canada.