Calling it a “a critical milestone in its fight against COVID-19,” Health Canada authorized the Pfizer Inc./Biontech SE COVID-19 vaccine for people age 16 or older.

The Dec. 9 authorization came just two days after the U.K. began administering the vaccine, which it conditionally approved last week. The U.K. was the first Western country to authorize BNT-162b2, making it the first messenger RNA drug to be approved.

The Canadian government announced earlier in the week that Pfizer is set to provide it with up to 249,000 doses of the vaccine during December. Since the vaccine requires two doses 21 days apart, that would be enough to vaccinate fewer than 125,000 people.

Health Canada began an independent rolling review of the vaccine Oct. 9. Based on studies in about 44,000 participants, the vaccine was 95% effective in preventing SARS-CoV-2 infections beginning in the first week after the second dose. “This means that people may not be protected against COVID-19 disease until at least seven days after the second dose,” Health Canada said.

The Public Health Agency of Canada added, “As welcome as this news is amid our ongoing concerns of rapid growth and increasing severe outcomes, it does not mean that control of COVID-19 will be soon or quick.”

As a condition of the Canadian authorization, Pfizer and Biontech must continue to provide Health Canada with information on the vaccine’s safety, efficacy and quality to ensure its benefits are demonstrated in the real world. The agency said the manufacturers plan to follow study participants for two years following their second vaccine dose.

The manufacturers also are testing the vaccine in children of all age groups to see if it’s safe for pediatric use.