Transport Committee on Dec. 10th, 2020

[Stephanie Kusie, Conservative, Calgary Midnapore, AB]

Thank you, Dr. Chagla.

I have a minute left, so I'm going to Dr. Bogoch, now.

Could you comment, please, on priority? You talked about surveillance. I'm wondering what entity would be responsible for that internationally. Would it be the IATA? Would it be the World Health Organization? Finally, as we see inequality within vaccination, perhaps you could comment on immunity passports, in 50 seconds, Dr. Bogoch.

[Dr. Isaac Bogoch]

That shouldn't be a problem at all.

Let's start with immunity passports. I think we need to poll the Canadian public, because there are very polarizing thoughts on this. I can certainly see some benefits and obviously some clear drawbacks, and especially some major equity issues with that.

With regard to surveillance on airplanes, I would see this as a public-private partnership. That's essential. We know that human mobility is responsible for so much of the transmission of infectious diseases nationally and internationally. Look at our non-existent influenza season we're having so far. I don't want to get too overconfident, because it's just the beginning, but we can see how human mobility significantly contributes to the spread of infectious diseases. Public-private partnerships, through some formal program that we can think of, be it the IATA or whatever, need to happen.

In terms of priority populations, I completely agree with Dr. Chagla. While front-facing individuals who are part of the essential functioning of society should be prioritized—that includes teachers and other members that Dr. Chagla mentioned—that certainly could include crew. That would be below the priority of people at risk of severe infections such as those in long-term care facilities, indigenous populations and other groups that were mentioned in the NACI guidelines as the first tier of people who should be vaccinated.

[The Chair, Liberal, Vance Badawey]

Thank you, Dr. Bogoch.

[Stephanie Kusie, Conservative, Calgary Midnapore, AB]

Thank you, Chair.

I was going to ask Mr. Taylor if he is staying at the Four Seasons in Mexico City. It looks familiar, but I'll save that for another round. Thank you.

[The Chair, Liberal, Vance Badawey]

Thank you, Ms. Kusie.

We're now going to Ms. Jaczek for six minutes.

Ms. Jaczek, the floor is yours.

[Helena Jaczek, Liberal, Markham—Stouffville, ON]

Thank you so much.

Thank you to all the witnesses for being here and giving excellent testimony. In particular, to the two physicians, thank you for what you've been doing in the news media. I've heard you both and I think you're really helping Canadians to interpret the situation with COVID-19.

Dr. Bogoch, certainly you referenced the precautions that are being taken on airlines. You know that Canadian airlines did follow IATA recommendations. They were instituted in July. You and Dr. Chagla both mentioned the filtration system and masking. There are also temperature checks.

If you look at data, are you able to...? Obviously none of these things, such as doing temperature checks, is in any way harmful. Are you able in any way to quantify the most valuable type of intervention? It sounds as though filtration and air turnover and so on are the most important? Would you confirm that?

[Dr. Isaac Bogoch]

Sure.

There are a couple of things to note. I helped with those IATA recommendations. A lot of those were conjured up in March in Singapore, which was my last trip before everything shut down, so I'm aware of those and I think they're pretty strong because there was broad consultation with the World Health Organization and ICAO as well.

The second thing is that I don't think there's going to be one step to make things safe. It's really a bundle of measures taken together that will make airline travel safer. As I mentioned, I really think we have to focus on the point of origin to the point of destination and everywhere in between. That will really ensure proper safety. Of course, there are only certain things that are under the control of the aviation sector, but if we really focus on a more holistic approach including education, we can make travel safer and instill greater confidence.

Directly related to the plane itself, the air filtration system and ventilation system on the plane are spectacular. If we couple that with universal masking, which is also extremely helpful, and really crowd control as best you can getting on and off the plane while that ventilation system might not be functioning, those are all very high-yield components. Of course, hand hygiene is also important and all the other public health measures that we've been discussing, but those would be the highest yield, in my opinion. Again, it's a bundle.

On the last point, temperature checks, it was really interesting—and don't laugh me off this call—that initially they weren't being done at Canadian airports and everyone said, “Whoa, we're not doing temperature checks. We need to do them.” Then they were doing temperature checks, and everyone was saying, “Whoa, they're useless. We don't need to do them.” It's optics. You're not going to get.... With this infection, you have to have the right fever at the right place and the right time, and there are a lot of optics. I don't think that's bad. It might give some people a little more confidence in travelling, but that in and of itself isn't going to make air travel safe.

[Helena Jaczek, Liberal, Markham—Stouffville, ON]

Thank you.

Now, turning to rapid testing, certainly in early days I think there was a lot of questioning around the reliability.

Dr. Chagla, could you inform us of what's being used now and what are the sensitivity specificities—false negatives, false positives—that you know of at this point in time?

[Dr. Zain Chagla]

The major rapid test that's available on the Canadian market right now is the Panbio by Abbott. This is a lateral flow assay. It looks very much like a pregnancy test. People get a nasopharyngeal swab. From what I understand, Health Canada is looking at approving nasal swabs to make it a little more tolerable. It's put into a tube; the tube is dropped onto a pregnancy test, basically, and you wait 15 to 20 minutes for a result.

Sensitivity—and again, this is approval, as compared to PCR—in people who are symptomatic is about 75% and specificity 95%. That being said, the sensitivity improves in people who have very high levels of circulating virus. One of the things that got discovered in the McMaster study...as we know, PCR tests tend to stay positive in some individuals for some time. It's not a reflection of their infectivity. It's a reflection of shedding virus.

That is a double-edged sword, in that sense, whereby if you PCR everyone who comes back, you may have a wait time, and you may get data that might not actually be usable. Dr. Smieja, who was part of that study, really did pick up a lot of people with what we call high-cycle thresholds of very low levels of virus. These rapid tests may pick up the people who are more clinically relevant, the people who are actually infectious and a threat to people, rather than picking up the people at the very early ends of their disease and at the very non-infectious late ends of their disease.

We are looking at these tests in long-term care and we're looking at these tests for surveillance for other populations, recognizing that in someone who's symptomatic, I don't want to give them this test necessarily on its own. But if it's someone who's asymptomatic and who's feeling fine and I get a positive, I'm treating that person as if they're positive, because they're probably asymptomatic, infectious and walking around.

It's a double-edged sword. I think these tests, as Dr. Bogoch mentioned, actually do have a role in this type of testing just for rollout, for lowering laboratory requirements. Again, if you use them serially, they're effective, too, as long as they're done properly. Plus, again, the training can be done outside of a laboratory, not in the laboratory.

[Helena Jaczek, Liberal, Markham—Stouffville, ON]

From previous testimony, we have heard of a role for potentially pre-travel testing. Perhaps, Dr. Bogoch, you could comment as to how you might see that we refine what we're doing now.

[The Chair, Liberal, Vance Badawey]

A quick answer, please.

[Dr. Isaac Bogoch]

Absolutely.

For rapid testing, I think we're just using that as an umbrella term. There are certain products available and there are going to be more that are going to come onto the market soon.

We have to remember that the goal here is not to detect infection. We're trying to detect people who are at risk of transmitting infection. That's the goal. It's slightly different. It's who is going to transmit, not who is infected. That's a separate question to ask, but that's the important question to ask, and that's what rapid tests are addressing.

The next thing is that I think there would be a role for them. They're not going to be perfect. Of course, they're not going to be perfect. It's not a foolproof, safe and perfect solution. It will just incrementally add safety to air travel if it is done pre-travel.

[The Chair, Liberal, Vance Badawey]

Thank you, Dr. Bogoch and Dr. Jaczek.

We've now heard from the Conservatives with Ms. Kusie and the Liberals with Dr. Jaczek.

Dr. Jaczek, when you were speaking and asking those questions, I was thinking that in your former capacity as the minister of health for the Province of Ontario you would be tackling some of these issues. I'm sure you think about that often.

Now we're going to the Bloc Québécois, with Mr. Barsalou-Duval.

Mr. Barsalou-Duval, you have six minutes.

[Xavier Barsalou-Duval, Bloc, Pierre-Boucher—Les Patriotes—Verchères, QC]

Thank you, Mr. Chair.

My first question goes to Mr. Bogoch.

When answering a question just now, you said that the principle transmission vector of the disease is human mobility.

You also said—I don't know whether it was you, but I'm sure that Mr. Chagla mentioned it—that the air filtration systems in aircraft and the wearing of masks make it quite unlikely that you will catch COVID-19 in a plane.

However, despite everything, if people move around—before or after flights—the risk of transmission is higher.

Would you agree with me on that?

[Dr. Isaac Bogoch]

Yes, I would certainly agree with that.

I can go on, if you would like.

Yes, as for the the flight itself, you certainly can transmit on an airplane. There have been credible cases of COVID-19 being transmitted on planes. We have to come away from this acknowledging that. It's just much less likely than what people would think.

Certainly, the other components of travel are also very important to address. We shouldn't just focus on that tiny part of the puzzle, which is the airplane itself. If we think more holistically, we can improve travel safety and instill greater confidence in the aviation sector by looking at every aspect of travel: getting to the airport, getting on the plane and going from the airport.

We can break it down—if everyone has time later—into each one of those components and how to make each one of those safer. I've thought it through with my colleagues, and we've written papers on this as well.

[Xavier Barsalou-Duval, Bloc, Pierre-Boucher—Les Patriotes—Verchères, QC]

Thank you.

Under those circumstances, we gather that, even though the planes and the airports are extremely safe, the risk is ever-present when travelling, because people are moving around.

My other question is about the reliability of the tests. I understand that rapid tests are going to detect some. It is like a filter, but the mesh on the net is of a certain size. As I understand it, cases where people have no symptoms or are in the early stages of infection will not be detected by rapid tests.

Are you at all concerned that a lot of people may slip through the net?

[Dr. Isaac Bogoch]

No. What I was mentioning before is that we're really looking for multiple tiers of protection, and the rapid test is just one of many levels of protection there. It will certainly provide incremental safety, but by itself, it's not going to be the saviour and make airline travel perfectly safe. It will certainly add incremental safety, though.

[Xavier Barsalou-Duval, Bloc, Pierre-Boucher—Les Patriotes—Verchères, QC]

I completely understand that it is an advantage to have it, because the test could well detect certain cases.

As for the reliability of these tests, data on false negatives and false positives from Quebec show possible errors in 20% to 30% of the cases. That is actually one of the reasons why the government is not using them at the moment.

Given such a high error rate, can we consider those tests to be reliable? I would like to hear Mr. Chagla's comments afterwards.

[Dr. Zain Chagla]

Yes, it's a single test, so you take the results along with the type of patient you are testing. If the probability of that person's having COVID is low—the person is asymptomatic and is feeling fine—and the test is negative, yes, the sensitivity says that we might miss a few of them and that that negative might actually be a positive, but the probability of that person going in being positive isn't that high to begin with.

You have to combine those things. There is also the use of serial testing, similar to what they're doing in Calgary—day two and day seven. That also helps with increasing that sensitivity. Even if you got caught too early on that first test, you still have time to get a viral load that's higher on the second test and get picked up.

Again, these aren't perfect tests. You'd treat them as positives, but you'd still do a PCR on them. We have other models of infectious diseases where we do a screening test and a gold standard test for positives. There certainly are ways to make it work such that you don't necessarily overcall positives.

In terms of the negatives, yes, it is the right context. Serial testing helps, but you could certainly miss a couple of positives here and there. It's much less likely in people whom you don't suspect as being positive to begin with, though. If I'm in an emergency room testing people and I get a negative for someone who has a fever and a cough, I'm not going to rely on that result. If I'm walking out on the street and I swab someone and it is a negative, and their probability of having COVID is zero and they're feeling fine, then, yes, I'm going to rely on that negative as a real result.

[Xavier Barsalou-Duval, Bloc, Pierre-Boucher—Les Patriotes—Verchères, QC]

In an ideal world, how would you make sure that you don't really miss any positive cases?

Just now, you talked about a period of seven days for isolation and tracking. In Quebec, the public health recommendation is often that people isolate for 14 days.

How do you explain that difference?

[Dr. Zain Chagla]

Most individuals who are positive, who have been exposed, show up with their symptoms early, in the first three to five days, post exposure. You can track people in terms of, “My family member was positive. I was exposed.” Their detectable viral load is often 48 hours to 72 hours before symptom onset, so you can kind of map out, from the gross majority of individuals, that they will show up positive by day 10 and they will have detectable virus by day seven. That's where that consolidation comes out and where the CDC guidelines have changed in the sense that you might miss 1% in that tail between 10 to 14 days, but it's very unclear if that's even clinically relevant in most individuals. If you release people by day 10 who are asymptomatic, you probably have caught most of your individuals there. If you want to release them earlier, by day seven most of those people who are symptomatic by day 10 should probably have a detectable PCR or molecular result at that point.

That's where that advice has come from. It's an evolving field. Again, 14 days was the standard from the beginning, but again, knowing the natural history studies of people after exposure, it's much more likely that the gross majority of individuals will be PCR positive by day seven and positive for symptoms by day 10.

[The Chair, Liberal, Vance Badawey]

Thank you, Dr. Chagla, and thank you, Mr. Barsalou-Duval.

We'll move to Mr. Bachrach from the NDP for six minutes.

Mr. Bachrach, the floor is yours.

[Taylor Bachrach, NDP, Skeena—Bulkley Valley, BC]

Thank you, Mr. Chair.

Thank you to all of our witnesses for appearing today.

Dr. Chagla, continuing the conversation around rapid tests, I'm really interested in this idea of comparing the risk between the current 14-day quarantine and what's being proposed under these rapid-test pilot projects. If you were advising a decision-maker, and the decision-maker wanted the lowest-risk approach to international travel, which approach would you recommend?

[Dr. Zain Chagla]

If you were looking for an outcome to have zero cases show up that could be infectious to the community, then, yes, you would go with the 14-day approach. You would miss one of 100, going down that road.

You know, when the CDC focused on shortening the quarantine period, it was accepting that a 14-day quarantine is hell for a lot of people. It is very difficult. You want to incentivize people to do the seven days properly rather than doing seven, taking a quick trip to the grocery store at day 10, and then.... You know what I mean.

If you were going for just numbers, then, yes, the 14 days would be adequate. If you were going for practical compliance of a population to adhere to a quarantine period, then day seven would present a whole better opportunity to get people out earlier and adhere to those first seven days, when they're critical, more than anything else.

[Taylor Bachrach, NDP, Skeena—Bulkley Valley, BC]

Thanks for that.

From the results of the McMaster study here at Pearson, it looks like of the 1%, 0.7% were caught in the first test and 0.3% after seven days. Those seem like really small numbers when they're expressed as percentages, but doesn't that essentially tell us that fully a third of the positive cases were missed in the first test?