Health Committee on Feb. 19th, 2021

[Marcus Powlowski, Liberal, Thunder Bay—Rainy River, ON]

We're here to talk about the variants, and certainly the one think that's spreading the most in Canada is the British variant, which, in my understanding, may be more infectious but the vaccines still work on it. It seems to me the biggest question concerning vaccination right now is how far we can go between the first shot and the second booster shot.

I know Moderna has done studies that show after one dose it has a 92% efficacy. I think you will probably be familiar with the data coming out of Quebec that showed that 80% of elderly people were covered after three weeks, and I think that 80% of health care workers were covered after two weeks. I know in Quebec the strategy has been to prolong the period between the first and second shot. Certainly if you can go three months, that will double our ability to get people vaccinated quickly. Let me throw in there that I think Israel had some concerns with one shot being effective in the elderly.

I know there may be some competing data out there, but I wonder if the Public Health Agency of Canada or NACI will be making recommendations about the interval between first and second dose, and at the moment what are those recommendations?

Thank you.

[Dr. Caroline Quach-Thanh]

I can take this one, if you don't mind, Mr. Chair.

You have seen that NACI had recommended, given the data on hand at the time of publication, that we ask that the two doses be given preferably within a 42-day window period. That was based on the fact that in the two phase three trials, the Pfizer and the Moderna trials, participants got their second dose between 21 or 28 days, up to 42 days, and that was an average estimate. We have now seen the data from both the U.K. and Quebec and we are aware that Quebec is using a three-month interval.

We are going to make a new recommendation, so we are currently working on that. But the main idea is to try to balance the advantage of spreading out an 80% vaccine effectiveness to more people, allowing then a population health impact that is usually greater. But I think the question that remains unanswered is the duration of that 80% protection. So we have asked the U.K. to come back next week to give us an extended view on their now six weeks of follow-up. Quebec will also come back to present updated vaccine effectiveness data.

As we move forward and we see we have some leeway, we are going to be able to allow for a longer interval. We do not want to have a falling vaccine effectiveness to the point where we could be at risk of seeing variants become a problem. That balance is not an easy one to tackle without data.

[Marcus Powlowski, Liberal, Thunder Bay—Rainy River, ON]

This is a second question on vaccines to cover the variants. My understanding is that Moderna and Johnson & Johnson are already working on tweaking their vaccines. It seems fairly easy with both of those technologies. There are minor changes on the spike protein and you change the vaccine a bit.

Are you going to require that the vaccine producers with these new tweaks go through the usual process of phase one, phase two and phase three trials, or can that be expedited given that so far it seems like the vaccines are safe as they are?

[Dr. Caroline Quach-Thanh]

From a NACI standpoint, we will follow what Health Canada allows. We hope it will not require phase one and phase two. The discussion is already ongoing, but I don't see anybody from Health Canada here, so I don't know if Kim wants to answer that one.

[Kimberly Elmslie]

I would say only that that is a question for the regulatory authority at Health Canada and one, of course, that we can take back and ensure you receive an answer to.

[Marcus Powlowski, Liberal, Thunder Bay—Rainy River, ON]

Let me ask a bit about prioritization. I want to give a shout-out in support of the police. I know that NACI has made recommendations about priorities.

I know, having spoken to the police in Thunder Bay, that they're in a bit of a difficult position. They are certainly at high risk. They are the ones who really can't keep their hands off people. They're at risk of having their masks removed. I'm not sure, but I think there have been cases within the police force here and a lot of people having to be off work. We have a limited number of police already. This is a big problem.

I know that the ambulance drivers are being immunized. I know at least some staff in emerg, where I used to work, are being immunized, but the police aren't. What is the plan in terms of prioritizing them?

[Dr. Caroline Quach-Thanh]

Mr. Chair, the difficulty here is that prioritization is a provincial and territorial aspect and decision. NACI has put frontline essential workers, including the police, as a stage two priority. They are there, at the same level as ambulance workers and the others. As long as the province you're in puts them on the list, it will happen. They have been prioritized.

[The Chair, Liberal, Ron McKinnon]

Thank you.

Mr. Thériault, you have the floor for six minutes.

[Luc Thériault, Bloc, Montcalm, QC]

Thank you, Mr. Chair.

I will take advantage of your presence, Dr. Quach-Thanh, to ask you some questions.

First, I would like to thank you for being with us again. You have come to see us a few times. I hope that we will be able to get a copy of your speech as well as all of the speeches that were given today. As yours was very technical, I'd like to try to put it all in a little simpler terms. People have concerns. Mr. Powlowski spoke earlier about the issue of a single dose and the interval between two doses. People are concerned about whether they should get booster shots.

The data presented yesterday by the Institut national de santé publique du Québec, or INSPQ, was quite intriguing. It was good news. Basically, the INSPQ told us that the first dose of the vaccine is 85% effective and that the second dose would only increase effectiveness by 10%. In addition, the second dose could increase the duration of protection, but it's unclear how long that duration would be. However, it is also possible that a single dose could lead to revaccination.

Given the fact that as many people as possible would need to be vaccinated to achieve herd immunity, what do you think of this news? Do you feel the second dose is necessary? Isn't it just a prerogative of a company that wants to promote its brand and make doubly sure that it's going to work? This information is a total game-changer.

[Dr. Caroline Quach-Thanh]

Thank you for the question.

I have read the data from the INSPQ, and it is very intriguing indeed. It's also very good to have 85% effectiveness in a very elderly and very sick population living in long-term care centres, or CHSLDs.

According to the immunological data, the second dose makes the antibodies become more mature and therefore much stronger and more active. It is as if a key fits even better in a lock, allowing for longer-term protection.

Using a single dose is risky right now since we don't have any data on a single-dose program. We may eventually get some.

For example, we have some data on the single-dose program with the Johnson & Johnson vaccine, but, given the little we know about it, that vaccine is slightly less effective against the South African variant. So the manufacturer is now conducting studies on adding a second dose to see if it will make any difference.

It's not so much the added 10% effectiveness that prompts us to give a second dose. It's really about longer-term protection. We wouldn't want to have to go through the vaccination process over and over again. We want people to be protected against the viruses that are circulating.

In addition, the study published by the INSPQ was conducted in Quebec at a time when we had no variants of concern. Effectiveness of 85% was only established for the field virus. We will need to continue to monitor. As Dr. De Serres said, when we see the effectiveness starting to drop, it will probably be time to give the second dose. For now, Quebec is planning a three-month interval between the two doses. So the initial deliveries will mean many more people can get vaccinated.

[Luc Thériault, Bloc, Montcalm, QC]

Yes, we can vaccinate people only provided that we have enough vaccines.

Do you know approximately when herd immunity could be achieved, in terms of time, not as a percentage? Do you know any scenarios to show that we could achieve it in October or September? If that were the case, what arrangements could be made be to ensure permanent immunity?

At the moment, it's not complicated, everyone has to be vaccinated. However, once we have done that, when do we have to revaccinate people so that we can continue to live with this virus?

[Dr. Caroline Quach-Thanh]

That's an excellent question, and my crystal ball is as good as yours.

Depending on the rate of vaccine deliveries, I have a feeling that we'll get there around the fall. We hope that about 85% of our population will be vaccinated by then.

Afterwards, it will be necessary to see the duration of the vaccine's protection. We have to be very honest, the phase III studies don't allow us to know the duration of protection of these vaccines. The studies showed that the duration of protection was 14 weeks. So there is protection for about three months after the second dose.

It's the ongoing monitoring that's going on that will allow us to tell how long we're protected. This doesn't necessarily mean that it'll be necessary to have a continuous reminder. It will depend on the variants and duration of protection.

According to our crystal balls, which are as good or as bad as others, we may need to be vaccinated every year, a bit like the flu, because there may be changes in the virus.

[Luc Thériault, Bloc, Montcalm, QC]

I understand that my time is up. I'll try to come back to it.

[The Chair, Liberal, Ron McKinnon]

Thank you.

We go now to Mr. Davies.

Mr. Davies, please go ahead for six minutes.

[Don Davies, NDP, Vancouver Kingsway, BC]

Thank you.

Dr. Quach-Thanh, does the emergence of highly transmissible variants of concern increase the level of vaccine coverage required to reach population immunity in Canada?

[Dr. Caroline Quach-Thanh]

It does. Herd immunity is based on the reproductive number, which was approximately three to four with the original virus. It's 50% more, at four to six, with those new variants. Therefore, you would need close to 85% of your population either immunized or protected through natural disease to be able to reach herd immunity.

[Don Davies, NDP, Vancouver Kingsway, BC]

Thank you.

That jives with research coming out of the University of East Anglia. They found that initially 69% of the population would need to be vaccinated with the Pfizer vaccine or 93% with the AstraZeneca to bring the R number below 1. But when they took into account that B.1.1.7 variant, they found that vaccinating the entire population with the AstraZeneca vaccine would only reduce the R value to 1.325. Meanwhile, the Pfizer vaccine would require 82% of the population to be vaccinated to control the spread of the new variant.

To the Public Health Agency of Canada, have you conducted similar modelling for Canada?

[Dr. Caroline Quach-Thanh]

NACI is not doing such modelling at this point in time. We're currently looking more at the deployment of vaccine and what category of people should be vaccinated to achieve the largest public health gains.

We can absolutely submit that question to the PHAC modellers.

[Don Davies, NDP, Vancouver Kingsway, BC]

Thank you. I'd appreciate that.

Do you expect that the U.K. variant, the South Africa variant or the Brazil variant will become the dominant strain of the SARS-CoV-2 virus in Canada? If so, when would you anticipate that this would occur?

[Dr. Caroline Quach-Thanh]

We sure hope not, but it's possible that it will come to life. I think at this point in time, we have the sense that the U.K. variant is the one that is the most prominent in most of our provinces. We're trying through various public health measures to limit the spread of that variant. Maybe we'll be better than other countries, because at least we know it's there, but otherwise, because it is just more transmissible, it eventually will take over.

We haven't seen much of the South African variant yet, at least not in Quebec. I think maybe Dr. Poliquin can answer more about that in terms of what is spreading. It is a concern, absolutely.

[Don Davies, NDP, Vancouver Kingsway, BC]

Thank you.

In terms of the volume, we know that cases of the B.1.1.7 variant have now been found in all 10 provinces. As of two days ago, Canadian health units had identified 673 cases of the B.1.1.7, B.1.351 and P.1 variants across Canada. Experts are claiming that the real total is likely in the thousands, since testing for the variants differs across Canada, and of course not everyone will get tested.

In your view, how close are we to having an accurate understanding of the prevalence of these variants in Canada?

[Dr. Caroline Quach-Thanh]

The NACI perspective has nothing to do with it, so I can only speak from the Quebec perspective, where every single positive case is being checked for variants.

As for the rest of Canada, I will refer to Guillaume.

[Dr. Guillaume Poliquin]

Through the existing infrastructure, as of December, Canada was able to sequence about 5% of positives. Efforts are under way to reach about 10% of all positives in Canada. That is a separate initiative to the rollout of screening assays to be able to rapidly look for variants of concern with a recognized genetic sequence. Efforts are under way through the Canadian Public Health Laboratory Network, with support from the National Microbiology Lab, to be able to screen all positives for—

[Don Davies, NDP, Vancouver Kingsway, BC]

Can you give us some context, Dr. Poliquin? I mean, 5% to 10% doesn't sound like much to me. Can you tell me this in layperson's terms? How accurate are we in identifying the prevalence of variants?

[Dr. Guillaume Poliquin]

There are two different thrusts to answer the question. One is the sequencing approach and one is the screen for variants, which uses different technology. Efforts are under way to be able to screen all positives for the presence of known variants with known genetic sequence.

When it comes to our overall sequencing capacity, we are on par with the leader countries in the space, including the United Kingdom, and are ahead of many other jurisdictions, including European countries.