TORONTO -- Health Canada’s approval of the Pfizer-BioNTech COVID-19 vaccine Wednesday clears the way to rolling out the distribution of the first 249,000 doses among prioritized groups.

In total, the federal government has purchased 20 million doses of this vaccine, and has an option to buy 56 million more.

The following is a transcript of CTV National News medical correspondent Avis Favaro’s interview with Dr. Jelena Vojicic, vaccines medical lead with Pfizer Canada.

Vojicic, who is located in Montreal, discusses her emotional reaction to the positive results in clinical trials, what this moment means in the battle against COVID-19, and how this vaccine could signal a breakthrough in vaccine development.

What is your reaction to the approval?

“I can say that we're very pleased with the announcement by Health Canada, about the authorization of the Pfizer-BioNTech COVID-19 vaccine. This is certainly a historic moment for science and for Canadians. And this is a result of tremendous effort, starting with the international scientific community and then going over the dedicated work of Pfizer and BioNTech employees, the clinical trial sites and clinical trials volunteers. And of course, I need to acknowledge the tremendous work by Health Canada in quickly reviewing our file while maintaining really gold standards of review and keeping a vigilant eye on the data.”

Where does Canada now rank in terms of approval?

“Canada is currently among the top three countries for the approval.”

When will the shipments arrive and where?

"So now that we have the authorization by Health Canada under the interim order, we are prepared to ship to the first sites that were identified by the provincial public health and governmental authorities, and we're expecting that shipment, basically, imminently.”

Are the shipments coming from Europe or the United States?

“So, there are a couple of sites that we will be using to supply Canada. Most of the shipments will be coming out of Belgium, and there is also site in Kalamazoo, Mich., from the U.S., but primarily our shipments will be coming from Belgium.”

How many vaccine doses will be in the first shipment?

“So I can’t give you the exact number of doses right now, but I know that Canada has secured the doses for December, which is excellent news, and we will be supplying those doses to the identified sites, as I mentioned, by the provincial authorities.”

Other vaccine makers are allowing the provinces to do their own shipping. Why is Pfizer taking control of the shipping?

“Well as I'm sure you've heard, the vaccine does require ultra-low temperature storage, and in being proactive in managing the vaccine appropriately to make sure its integrity from the manufacturing site to the actual site of use, we proactively actually designed specific thermal shippers that are capable of maintaining the required temperature. And these thermal shippers are also equipped with GPS-enabled data logger that records the temperature as well as the location of these shippers. So, at any point of time between the manufacturing site and the point of use, we will be able to track those shipments and prevent any unwanted temperature excursions.”

We've heard reports that some people will try to intercept vaccine shipments. Is security of the shipment an issue?

“I don't think the security of the shipment will be an issue. We are taking steps to send the shipments to the point of use in an appropriate manner. So, as I said, you know, everything is monitored from the manufacturing site to the point of use, so any deviations, any issues we would be alerted about.”

We have heard that the President of the United States may enact some laws that may stop shipments coming from the United States to other countries. Have you looked into that and is that a concern for you?

“I wouldn't want to speculate on what may or may not happen to that point. As I mentioned, we do have multiple sites around the world (and we are) currently prioritizing some of the sites but if we ever anticipate any of such issues we do have contingency plans to address it.”

The data that Pfizer released to the FDA today suggested that one dose might have considerable benefit. Are you looking into whether two doses are necessary or are there adjustments being considered at all?

“So the vaccine has been studied for the primary endpoint prevention of symptomatic, COVID-19 (in two doses) which are given 21 days apart, and that is how the vaccine has been authorized for use. So, for the use of vaccine we do recommend and Health Canada recommends two doses given 21 days apart.”

Are you going to be able to produce the amount of vaccines that you have promised Canada? Because there were some considerations last week that you might not have enough raw material or there might be some interruptions.

"As you know, the production of the vaccine has started early on and ramping up of the production has started early on in order to ensure that we do have enough vaccine for the population. Now, for Canada specifically, our agreement with the Government of Canada was for 2021. Given that we are bringing the vaccine earlier on, I think we can be reassured that we do have the doses required for Canada.”

Why are you able to bring them earlier if the contract was for 2021?

“There are many factors that played into that. One of the key factors is the ability to conclude the trial and get the results, as well as the ability for the regulators to leverage the interim order, which (allows) ongoing access to the data, and to review that data more or less in real time. So therefore, cutting the lengthy process that would come after the regular submission. So the regulators had access to the data earlier and they were able to do their thorough review and to pull that authorization forward … and we were able to secure the doses a bit earlier than initially planned.”

Have you ever seen a vaccine development go this fast?

“It is really extraordinary that we are able to be where we are today. But I will reassure you that in that development, in the clinical development process, nothing was shortchanged, no steps skipped. So, the trials and all the elements of the clinical development were conducted, including preclinical and early clinical phase and late clinical phase. And it's really the tremendous effort, the mobilization of the assets, the ability, again, to to have the ongoing dialogue with the regulators, as well as the … manufacturing early on, which we don't typically do, which enabled really to pull that timeline forward and have this tremendous, really historic, moment today.”

Some of the scientists that we've spoken to, when they saw the data being so positive, they actually expressed an emotional reaction to it. Did you have any reaction when you looked at the data?

“I did. You know it's months of work at risk, right, and when you see something as encouraging as the data that came through, you know, one cannot help but tear up and I'm, you know, it does get emotional. Absolutely.”

What does this signify?

It's really a historic moment for the science. This might change the way we do clinical trials and vaccine trials. New technologies are enabling us to do things differently, so this is really unprecedented, and that gives sense of pride and sense of satisfaction when you're involved in something like that.”

You are in Montreal, a city and province that has suffered. Do you see a vaccine as a way out of the mess that we’re in?

“I think it's still early to speculate on how will 2021 look from that perspective. I think it's going to be important to keep following the recommendations by public health, to follow their guidance. Hopefully, depending on how well the update goes of the vaccine (and) if we see other vaccines, how efficacious those will be. Those are all the determinants or all the elements that will determine what 2021 may look like.”

Can you say yet how long the immunity will last from your vaccine?

“The scientific community is looking, even at the duration of natural infection, so that's a matter of ongoing study. From our vaccine perspective, specifically, we will continue to look at the data and we'll continue to follow the 44,000 participants in the trial. The trial will be ongoing for another couple of years so as we collect more data, we hope to get more information and more understanding of the duration and the elements required from the immune response.”

Is the mRNA vaccine technology the beginning of a big change in vaccine production?

“If it works, potentially so. It is newer technology. It is different from what we have seen so far in terms of vaccine production. It does not utilize the weakened or the dead virus. It does not utilize the parts, the non-immune parts of the virus. What it does, it utilizes part of the genetic code of the virus to give the instruction to ourselves to produce that part that's important to protect against. So I'm sure you've heard about the spike protein or the S protein; it's the little spike that gives the coronavirus its look. That is what the mRNA is teaching ourselves to produce and then that spike is presented to our immune system and the immune system is then activated and learns about this fight, so that when the real virus comes along, we can be protected. So, the technology’s nimble. The production can be scaled up quickly. This may be the new way we will be addressing some of these infectious diseases.”

Whose responsibility is it to monitor the side effects once the vaccine is rolled out in Canada?

“Well, it is basically a joint responsibility. First of all, we will continue to follow the participants in the clinical trial, and it's a large number of participants that we're following. I will just mention that in a clinical trial of this size we can see all sorts of different things and we collect safety events regardless of their relatedness to the vaccine. So it is not unheard of or unusual that we do see cases of different illnesses. During the trial, there is an independent data safety monitoring board, which is a group of experts that do have expertise in clinical trials and specifically, in vaccines. So those are infectious diseases experts that were monitoring safety on a weekly basis and have not signalled any significant safety concerns. After the vaccine is rolled out there are also checkmarks in place and we continue to do what we call pharmacovigilance. In other words, we continue to collect the information about safety events as the vaccine is rolled out into population. Public health, as well, will be looking at or collecting the data.”

Can people who already have had COVID-19 be vaccinated with your accine?

“In our trial we did include individuals who had previous signs of infection. So again, no safety concerns were raised for this particular population.”

This interview has been edited for clarity and length.