Health Canada has approved the first COVID-19 vaccine, with the approval of a second vaccine on the horizon.

Officials announced the approval of the Pfizer-BioNTech vaccine during a press conference on Wednesday. The drug has a 95 per cent success rate, with no major safety concerns, according to a regulatory decision summary published on the federal government’s COVID-19 website.

Dr. Supriya Sharma, Health Canada’s chief medical advisor, said the approval marks a critical milestone in their efforts to control the virus’ spread. On Wednesday, she sought to assure Canadians that the vaccine was safe for public use.

“First and foremost, the authorization follows a really rigorous review of all the scientific and technical data from the clinical trials and all the manufacturing and all the pre-clinical data, and all the research that has gone into the vaccine so far,” Sharma told reporters. “When we do an authorization, it means we looked at it, and the benefits outweigh the potential risks.”

Health Canada conducted a rolling review of the Pfizer vaccine, which is designed to speed up the review process without sacrificing quality. Typically, reviews wait for all testing data to come in before starting the process, but rolling reviews assess data as it comes in instead of waiting for the whole package. Sharma said that gives reviewers more flexibility.

Experts in the field of clinical medicine, biochemistry and immunology where among those who oversaw the review.

The regulatory decision summary listed a number of minor side effects caused by the vaccine. The biggest was injection site pain, which was reported in 84 per cent of those who received the vaccine. Other side effects include fatigue, which was reported in 62.9 per cent of participants, followed by headaches (55.1 per cent), muscle pain (38.3 per cent), chills (31.9 per cent), joint pain (23.6 per cent) and fever (14.2 per cent).

Sharma and Dr. Marc Berthiaume, the director of Health Canada’s Bureau for Medical Science, said Canadians could still trust the vaccine, since the positives significantly outweigh the negatives.

“The Pfizer vaccine was examined rigorously, which does not mean there are no side effects,” Berthiaume explained. “We are actively working on monitoring these side effects. What we can say is we have excellent data on a large number of people, which characterizes the risk profile and the risk-benefit profile rigorously. The assessment was done rigorously. We can reassure Canadians that getting the vaccine is a benefit to them.”

“It is still a vaccine, and there are potential risks, even if they’re rare,” Sharma added. “That’s why it’s important that we continue to monitor it. I would say to Canadians, we’ve authorized it, (and) if it is their turn to get the vaccine, they absolutely should feel comfortable getting it, but we still do need to continue to monitor it as we would any product.”

As part of the approval, Pfizer must monitor the vaccine and immediately report any problems to Health Canada. When asked if public health officials would monitor the data independently, or rely on Pfizer to report any problems, Berthiaume said they were already in contact with public health officials in other countries to form an independent network.

Health officials in the United Kingdom have already warned people with significant allergies to avoid getting the Pfizer-BioNTech vaccine after two patients suffered adverse reactions to it. Canadian health officials have already approached their counterparts in the UK for more information.

“There are multiple systems in place to closely monitor the safety of the vaccine,” Berthiaume said. “The approval was done very rigorously, but we are also very closely following the evolution of the drug on the market, in cooperation with multiple partners.”

There are three more COVID vaccine candidates still undergoing the review process. The Moderna vaccine will likely be the second one approved. Berthiaume said they have no definitive date for when that will be, but he expected a final decision “shortly.”

Canada has agreements with seven companies to provide COVID-19 vaccines once they become available.

Health officials say the initial supply of the Pfizer-BioNTech vaccine will be limited. They’re expecting larger quantities by Spring 2021.