Small Changes Big Impact
Small Changes Big Impact
Using what we know about influenza to put the novel coronavirus into perspective with Dr. Jeff Kwong
In studio today, we have Jeff Kwong, family doctor at Toronto Western Hospital, and a senior scientist at ICES and at Public Health Ontario. He's also professor at the Department of Family and Community Medicine and cross appointed at the Dalla Lana School of Public Health at the University of Toronto. Today's episode focuses on using what we know about influenza to put the novel coronavirus into perspective.
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Small Changes, Big Impact: a DFCM podcast. I'm your host, Dr. Jeremy Rezmovitz. In studio today, we have Jeff Kwong, family doctor at Toronto Western Hospital. He's a senior scientist at ICES and at Public Health Ontario. He's also professor at the Department of Family and Community Medicine and cross appointed at the Dalla Lana School of Public Health at the University of Toronto. Today's episode focuses on putting the novel coronavirus into perspective. I hope you enjoyed the show. Welcome Jeff.
Dr. Kwong:Thanks.
Dr. Rezmovitz:So Jeff, tell us about the work that you're doing in influenza right now.
Dr. Kwong:Yeah, so I'm an epidemiologist and I do a fair bit of work around influenza vaccines, how effective they are. So we've been doing some studies looking at how effective influenza vaccines are in preventing lab confirmed influenza in various populations. So we've looked at young children, pregnant women, people with chronic obstructive pulmonary disease, and people who have a history of cancer, and we've shown in all these populations that influenza vaccines do work generally to prevent influenza infection.
Dr. Rezmovitz:So that's interesting because most of the patients that come in to my clinic tell me it doesn't work.
Dr. Kwong:Yeah, I think it's really tricky. I mean, I think there's a lot of things going on because influenza season happens during respiratory virus season. So there's lots of other respiratory viruses that are circulating at the same time. And influenza vaccines are only designed to prevent influenza infection. And so a lot of people may get other respiratory infections and then they may say that's influenza and really it could have been another virus that they got. And then in addition to that, sometimes it's hard to predict which of the strains are going to be circulating in an upcoming season. So sometimes they do pick the wrong strain, and it is a lower efficacy vaccine. So there is some truth that the influenza vaccine doesn't work as well as other vaccines do, but I think some protection is better than no protection. And I think that's the way that people should think about it. You know, similarly to if someone has high cholesterol levels and we recommend that they take statin medication for the high cholesterol levels to prevent a heart attack. Well, I mean, those statins are only maybe 25% effective in reducing your chance of a heart attack. And no patient will say,"Oh, I'm not going to take a statin because it only reduces my chance of a heart attack by 25%." But if they say,"Oh, this influenza vaccine is only 20 or 30% effective and I'm not going to bother getting it," I think that's the wrong mentality to take.
Dr. Rezmovitz:So I guess there's two questions here. One, how do they determine that it's only 20 to 30% effective? Let's start with that question. How do they come up with that?
Dr. Kwong:Yeah, so we do these studies. So right now the most popular design is called a test negative design. So we find people who are symptomatic and then they get tested for influenza. And then we see if they test positive or negative, and then we look at their vaccination history. So we take the group that are test positive- and we call them cases- and we see what percent of that population got vaccinated. And then we look at the people who test negative and we call them the test negatives, and we look at what percent of those people had influenza vaccine. And so then by comparing those two groups, then we can come up with an estimate of vaccine effectiveness. And those are the studies that we read about in the news every year saying,"Oh, this year, the estimate- it was only this effective or higher." And it depends on the strains that are circulating as well. So there's really three VE estimates during any given season because there's a VE estimate for each strain that's in the vaccine.
Dr. Rezmovitz:Sorry- VE?
Dr. Kwong:Vaccine effectiveness.
Dr. Rezmovitz:Right. Okay. Just for anyone listening that didn't follow through. I just- acronyms do that to people.
Dr. Kwong:Yeah.
Dr. Rezmovitz:So what are the- there were, I believe three different flu vaccines available this year. There's a three Valent dose. There's a three Valent high dose and then a quadrivalent dose. Is that correct?
Dr. Kwong:That's right. Yeah. So there's both trivalent and quadrivalent, and then the high dose and standard dose. And this year there's no live attenuated influenza vaccine or flu mist, unfortunately.
Dr. Rezmovitz:So let me interpret what you just said. So you can't get the flu from the flu shot this year.
Dr. Kwong:That's right. All of them are killed vaccines. So it's impossible to get influenza infection from the vaccine.
Dr. Rezmovitz:Right. So any patient that comes in and says,"no, I got the flu from the flu shot"- it is possible if it was a live attenuated flu shot to get the flu from, but this year it is impossible.
Dr. Kwong:Correct.
Dr. Rezmovitz:Okay. And so of the three different vaccines that are available this year, have you- do you guys have preliminary data on the effectiveness of it?
Dr. Kwong:No, unfortunately they're not available yet. So we have to wait for the interim estimates to come out.
Dr. Rezmovitz:No problem. And so, just for everyone's edification here, how many different strains of influenza are there roughly circulating in Canada in winter time?
Dr. Kwong:Yeah, there's a handful that are circulating at any given time, and public health folks are doing surveillance to see what circulating at any given time. So there's normally- the most common ones are there's an H1N1 strain, an H3N2 strain, and then B strains. And of the B- they break it down further into the Victoria and Yamagata lineages. And so these are the four main groups that are circulating. And sometimes one is more predominant than the other. So let's say some seasons, you could have H3N2 predominant, some seasons can be H1N1 predominant. So it's really a very fluid situation. It can change. In some seasons, we've seen multiple strains circulating at the same time.
Dr. Rezmovitz:But for a ballpark, how many different permutations and combinations of flu are there? Are we talking 10? Talking 20?
Dr. Kwong:It's really, really hard to say because at what point do you call it a new strain? So, influenza is a very sloppy virus in terms of how it replicates. So it's always introducing these mutations and it's constantly drifting- that's the term we use. And so at what point- you have like one point mutation and then another point mutation and then when did it become a new strain? And so it's really hard to really classify exactly how many strains there are, but we can see that when we- and these days, we've got better technology, we can actually do all the sequencing of the specimens of the viruses that w e're isolating. And we're seeing that there's a huge heterogeneity- diversity in these viruses that were isolating.
Dr. Rezmovitz:And so I think actually if people are watching the news these days, there are other viruses that are circulating along with- concurrently with the influenza virus.
Dr. Kwong:That's right. And so a lot of news right now is this new coronavirus that they've identified. They're calling it the 2019 novel coronavirus.
Dr. Rezmovitz:And so, have you guys done any research on that right now?
Dr. Kwong:No. So I haven't been directly involved in any of the efforts there and there's not much research going on there outside of China. There's a lot of research going on in China at the moment.
Dr. Rezmovitz:So, but it seems to me that as a virus- as a respiratory virus, that if we were to just focus on influenza for a second, just getting your flu shot isn't enough. I mean we can't think of protecting ourselves using one method for- in isolation or one method solely against trying to contract influenza. To me, I would think there are other methods that you can use to reduce the contagiousness. Is that even the term that we use- to reduce the contractibility of influenza, like washing your hands. And so, in the same way that you said that if somebody took a statin, you get a 25% reduction- again, we don't just use statins to reduce the risk. We use physical activity, we use diet, we use sensibility, we look at other medications that we can use in tandem with this strategy. So what other strategies can you suggest to reduce the risk of transmission of influenza and possibly the novel coronavirus?
Dr. Kwong:Yeah, absolutely. So I mean, I think the number one is hand-washing. So do it often and do it well.
Dr. Rezmovitz:Is that with soap or without?
Dr. Kwong:Either soap and water or with hand sanitizer. So alcohol based hand sanitizers are effective.
Dr. Rezmovitz:I want to tell my son that. If he listens to this, I want him to know because sometimes he just doesn't wash his hands.
Dr. Kwong:Yeah, I know. It's so hard to tell our kids. You know, that's the one thing, like the parents always nagging their kids-"wash your hands, wash your hands." But definitely washing your hands is the number one thing to help protect us against all respiratory pathogens.
Dr. Rezmovitz:Right.
Dr. Kwong:And then, things like staying home when you're sick. So we call this social distancing. And respiratory etiquette where you cough into your sleeve or sneeze into a tissue and throw it out and then wash your hands after that. So all of these things- and then the usual things to stay healthy like get enough sleep, have a healthy diet, get exercise. All of these things can help us stay healthy during respiratory virus season.
Dr. Rezmovitz:Definitely. And so as an epidemiologist, have you noticed any surges of influenza so far this year?
Dr. Kwong:Oh, definitely. We've already seen the outbreak- the surge in influenza. And I haven't been following it lately- I'm not sure if it's going down yet. Typically, it starts to increase in December, and then it goes up further during the Christmas holidays, and then sometimes it comes down earlier during January, but sometimes it can go on throughout January and February. Sometimes we get a double peak, so there can be a first peak and then it goes down and then we have a second peak later. So it's really unpredictable and we really don't understand how the viruses behave and what's driving the epidemics every year.
Dr. Rezmovitz:So we don't know what causes these surges.
Dr. Kwong:No, surprisingly we actually don't. I mean, there's lots of theories. We think it may be related to the weather- so like colder weather, dry, lower relative humidity seems to- at least in temperate climates- seems to drive influenza transmission. And then some people think it may be like air pollution. Maybe people- gatherings and stuff like that. So like over the holidays when people are gathering that might be more. And then also in schools, kids are transmitting it from child to child.
Dr. Rezmovitz:I got to talk to my kids' teachers about why they're doing that. No, it just seems weird that these are all associations. We have no causation yet for why in certain parts of the winter months, the influenza spikes because, correct me if I'm wrong here, but influenza actually circulates all year round.
Dr. Kwong:Well in temperate climates, we don't see very much of it outside of influenza season. I mean there might be the odd case of people traveling from other parts of the world, but- and this is a mystery where we don't know why it disappears every spring. It hasn't affected the entire population yet. It's not like there's an absence of hosts, but for some reason it just goes away. And so that's one of the mysteries we haven't figured out yet. In tropical areas, it does circulate year round. So if you're closer to the equator, it is circulating year round, but in the temperate area- so further away from the equator- there's definitely seasonality.
Dr. Rezmovitz:There's definitely seasonality. But I guess one should be wary that if we are moving towards less seasonality with global climate change, t hen it is possible that this virus will continue to move north. It will march north of the tropics and start circulating yearly.
Dr. Kwong:Year round, you mean.
Dr. Rezmovitz:Sorry. Year round.
Dr. Kwong:I'm not sure that climate change will lead to loss of seasonality. I mean, I think there's just more extreme weather events, but I don't think it means we're going to stop having winters.
Dr. Rezmovitz:Yeah. They just might not be in January anymore. So given that we've already had a surge this year and the unpredictability of the virus, would you say people can not worry about getting their flu shot anymore?
Dr. Kwong:Yeah, I think it's still a good idea to have it if you haven't had it. I mean, you could make the argument that given that most of it's past, then the value of getting it this year might be lower. And maybe it's worth saving it until next year. So it's a tough call, but I think given what's going on right now, it's not like influenza has completely eliminated. So I think it still is worthwhile getting, especially if you're in a high risk group.
Dr. Rezmovitz:And is there any chance that an influence of vaccine given this year of the strains that they've picked- let's say there's a year that there's a mismatch in the circulating strains and the strains they've picked for the influenza vaccine. Is there any chance that by getting the vaccine, it will confer benefit in three or five years when that vaccine, when that flu starts circulating in- that strain circulates?
Dr. Kwong:That's a really good question. I think the issue is that, you know, when we do these characterizations, we look at the antigenic differences. So it's like how well, like it's like a certain lab test they do to see how antigenically it's different from the vaccines strains. And then they also look at genetic differences, which are slightly different from antigenic differences. And so, sometimes they see things that look antigenically different or genetically different, but maybe there's still some- the vaccine effectiveness is actually comparable to one where there's a match. So there's suggestion of there can be cross protection between strains and this is something that we don't fully understand, so we have to do kind of all three types of studies and we kind of come up with whether it was actually a mismatch or not mismatch. And it's hard to- it's not like a black and white thing to say this was a mismatch or not mismatch. It's very much a grey zone- like subtleties, like degrees of gradation.
Dr. Rezmovitz:Of course.
Dr. Kwong:Yeah. But to answer your question- sorry, I didn't answer your question. So the vaccine is supposed to protect against this season's strains and there's some studies that suggest that the vaccine protection doesn't go beyond the season. And then there's other studies suggest that vaccine protection can go beyond the season. So both could be true. And so it's possible that maybe it can evolve back to the ones that were in this season's strains and maybe you could have kept production down the road. So I think that's a long way of saying that we don't know the answer yet.
Dr. Rezmovitz:Okay. That's a long way of saying we should err on the side of hope and get your flu shot. So, as a family doctor working in the community, do you have any suggestions- community or an academic health science centre- do you have any suggestions for family doctors working on the front lines or healthcare providers? Family, doctors, nurses, physician assistants, even our receptionists on the front lines that we can- some things that we can do to help protect against respiratory viruses, whether it's influenza, whether it's novel, new coronavirus and anything else that- how about old coronavirus called like the common cold? Things that we can do to protect ourselves in the office? Common little small changes that might have a really big impact.
Dr. Kwong:Well I think the first thing is what we call screening- active screening, where we ask the patient,"why are you coming in?" If they say"I've got fever and cough, other respiratory symptoms," then when they come in, they're not sitting in the waiting room for like half an hour, an hour, spewing and coughing and infecting the other patients in the waiting room. So you'd want to get the mask as soon as they get into the office or tell them to put a mask on before they come to the office. And then you try to put them into an exam room right away, so that we can reduce the chance of transmission to others. And then you can have things like passive screening where you can have signs up to tell people, if you're sick, then tell us- let us know so you're not sitting in here and spreading your infections. So if you are seeing patients and we should use precautions like- so I mean right now the Ministry has put out guidance saying that in the primary care setting we should be using N95 masks if we have them. And then also to wash your hands very frequently and to use other personal protective equipment such as face shields and gowns and gloves if we have them, especially if we're collecting specimens from them for the novel coronavirus.
Dr. Rezmovitz:So those are excellent screening opportunities that we have in the office, but as healthcare providers, who should we be listening to? There's so much media being pushed out on us from the CFPC, the OMA, the WHO, Public Health Ontario- who do we listen to? And what are the guidelines right now for family doctors regarding the novel coronavirus?
Dr. Kwong:Well, I think there is consistency amongst all the groups. And I think they are having a lot of communication, so at least at the federal level and the provincial level and the local level here in Canada. So I mean, I think depending on where you are, you would want to follow the local and provincial guidance. And so here in Ontario, we would be listening to the guidance from the Ministry of Health and from Public Health Ontario, and then also in the local health units here in Toronto- Toronto Public Health. And I think the guidance is consistent across all of them. I think they're saying- right at this moment they're saying we should be screening and consider testing for symptomatic individuals who have a travel history from Hubei province, which is where Wuhan is, or people who have had contact with people who've traveled recently in the last 14 days. But I suspect that they're going to be changing that to all of China because the CDC has now changed it to all of China because they have seen that the virus has spread to other areas in China already.
Dr. Rezmovitz:So what is the protocol then, for testing? Is it a nasal swab? Is it a nasal pharyngeal swabs? Is it a throat swab?
Dr. Kwong:Right now it's supposed to be three specimens. So one is a nasal pharyngeal swab, one is a throat swab, and then the other one is sputum if we're able to get it. And so the reason they're doing this is that they can test for not just the novel coronavirus but they're going to test for other common respiratory viruses as well as some bacterial pathogens as well.
Dr. Rezmovitz:And do you know if there are kits available yet that we can order from Public Health or from labs in order to provide nasal pharyngeal swabs?
Dr. Kwong:Well, I think that the standard swabs that we would get- usually that we have that we should have in our offices already. They're the standard ones that we have that we get from Public Health lab.
Dr. Rezmovitz:And do we- I assume we use a Public Health requisition in submitting- I just don't know if there's a code yet for novel coronavirus.
Dr. Kwong:That's right. I think first of all, we actually have to call Public Health Ontario to get permission to submit the specimen. So just to get clearance- so first of all, you'd want to speak to the patient and make sure that this is an appropriate person to be testing. And then you speak to the customer service representative at PHO, where they would say,"okay, this is what you do." And then you caught the specimen and then submit it. So it would be couriered to Public Health Ontario and test it right away.
Dr. Rezmovitz:And you know what, for purposes of the show, I think we're going to provide the Public Health Ontario phone number in the show notes. I don't know if you know it off the top of your head.
Dr. Kwong:Not off the top of my head.
Dr. Rezmovitz:No, neither do I. Maybe tomorrow. So that's excellent. Is there any final things you want to impart on our listeners today that can help us with the hysteria of the- I believe it's a P H E I M C, right? It's a public health emergency of international concern?
Dr. Kwong:That's right. I mean, I think it was appropriate for the WHO to make that declaration to prepare other countries to get ready for the situation. I think we're learning a lot. Every day we're seeing more cases and we're learning a lot about what's happening. You know, as of the last calendar, there had been more than 17,000 cases and about more than 360 deaths in China. But I think what we're learning is that a lot of the- I mean, I think this is a coronavirus like SARS was and like MERS. But I think they're very- I think it's might be different than the other two where we saw. But those other two, I think we saw a lot more severe illness. And I think with this one, I think we're going to see a lot more milder illness. And so, I think- there's 17,000 cases or more that they've already identified in China, but my guess is that there's actually many more out there that are- they're waiting for the test results to come back. So there's probably more cases that are going to be lab confirmed. And then there's others out there that have like milder illness that aren't being picked up. And so, I think we should put this into perspective of other respiratory viruses like influenza where we don't take that- we don't freak out over influenza, but my guess is that there's going to be similarly- a lot of mild cases and only the tip of the iceberg that's going to be really severe.
Dr. Rezmovitz:Yeah, definitely. I don't think most people realize that influenza is the sixth leading cause of death in Canada. And most people just kind of take it for granted. We don't actually use all of the resources that we have, as I still have flu shots available in my office, and people are still declining the flu shot, even though we have resources to fight against the flu. And yet, if a virus came- a virus- if a vaccine came out against novel coronavirus, I think there'd be people who'd be like,"I want that." So maybe we can drum up hysteria against influenza and then people will get their flu shots.
Dr. Kwong:Yeah. I mean, sometimes it just happens inadvertently, right? Every year when there's a teenage hockey player who dies from influenza, then that's when all the parents go and get their kids vaccinated. That's what happened during the 2009 H1N1 pandemic, is when there's scary stories like that, then that's when people would go and get the vaccine.
Dr. Rezmovitz:Well, something to consider. Thank you so much for coming in today. I really appreciate it.
Dr. Kwong:Okay, thanks Jeremy.
Dr. Rezmovitz:Take care.
Dr. Kwong:Okay. Thank you.
Dr. Rezmovitz:This podcast was made possible through the support of the Department of Family and Community Medicine at the University of Toronto. Special thanks to Allison Mullin, Brian Da Silva, and the whole podcast committee. Thanks for tuning in. See you next time.