Coronavirus (COVID-19): Press Conference with Stephen Kissler, 07/22/20

You’re listening to a press conference from the Harvard T.H. Chan School of Public Health with Dr. Stephen Kissler, research fellow of the Department of Immunology and Infectious Diseases. This call was recorded at 11:30 a.m. Eastern Time on Wednesday, July 22nd.

STEPHEN KISSLER: Briefly, to put the last week or so in context, we’ve seen these persistent increases in coronavirus cases across a lot of different states. Also, a rise in the associated deaths that have been delayed, but nevertheless seem to be increasing, especially in the places where we saw some of the earliest rises. Then I think the other thing that seems to have been on a lot of people’s minds lately is the reopening of schools. So I’d be happy to talk about any of those things as well as whatever else might be of interest today.

MODERATOR: Thank you, Dr. Kissler. OK. Looks our first question.

Q: Hi, Dr. Kissler, thank you for taking our questions this morning. I would like you to comment, if you can, on what I call the “cafe culture”. Starbucks, the big chains, Dunkin Donuts, have all taken a lot of measures to protect people, customers and their staff, including requiring face coverings. Now, when you come in, plexiglas barriers, regular disinfecting and so on. But some have eliminated indoor seating altogether and others haven’t. As you might imagine, there are people who work at Starbucks, linger, socialize and so on. So I’m wondering if you can comment on first whether you think the precautions are sufficient for indoor spaces that can vary a bit in size. Some of the Starbucks vary in size. Then, part two of that is to comment on the indoor seating where potentially people could linger for hours regardless of whether the tables are spaced further apart. So it’s not the same seating they might have had before. They’ve taken out soft leather chairs and so on, but they’re still allowing people to potentially linger there.

STEPHEN KISSLER: Yeah, definitely. So I think it’s worth mentioning that we are still at a point where we have a pretty good understanding of the different ways that we can reduce the probability of transmission, but we’re still figuring out what exactly the order of the importance of those things are and how they sort of interact with one another. As we’ve sort of known over the last weeks and months, it really seems like indoor settings are much higher risk for transmission. And so I think that is definitely encouraging that they’re taking all of the measures that you listed before. I think that all of those things together, including sanitizing and plexiglass and masks and these sorts of things definitely will help reducing the probability of indoor transmission for sure.

There’s been a lot of talk lately about droplet spread versus airborne spread. And all of this sort of happens within a continuum. We’re secreting droplets from respiratory droplets. Some of them are droplets, some of them are airborne, and the degree to which that matters for transmission changes. But, definitely long periods of time inside, even if tables are spaced far apart, the longer you spend indoors with someone else, the more likely it is for transmission to happen. So one of the key elements for, I think, reducing the possibility of indoor transmission if these cafes do allow people to linger for a long time, is making sure that there’s plenty of ventilation. Making sure that there’s airflow through the venue, wherever they are, to basically just prevent the buildup of virus particles in the air. And again, we’re still not entirely sure quite to what extent that contributes to transmission, but based on household studies, where coronavirus does seem to spread pretty readily within households, it seems like prolonged exposure indoors is definitely a risk factor.

So I think that’s what I would recommend. I would definitely commend all of the efforts that they have put in place so far. I think that indoor dining is a risk for sure, just like anything is that we do with respect to our outdoor behaviors and indoor behaviors during this pandemic. But I think that there are ways to even reduce the risk of transmission indoors, including through ventilation and maintaining distance. It’ll never be down to zero. But in the spectrum of things, it seems like a possible thing to do, say relatively safely.

Q: Just a quick follow up. Are you referring to HEPA filters, those they call high efficiency? And should it be a requirement at this point?

STEPHEN KISSLER: Well, I mean, that would certainly be helpful. But I wasn’t referring to that in particular. I think that even keeping windows and doors open and making sure that there’s a fan circulating air through the building can be helpful. HEPA filters great. But I think that that requires quite a bit of infrastructural change to establish something like that. So in the absence of that, definitely just keeping the air running through will help.

Q: Even if it’s air conditioning?

STEPHEN KISSLER: You know, I’m not actually familiar with the distinction between air conditioning and actually circulating outdoor air readily through the building. So I don’t think I can speak to that reliably.

Q: All right. Thank you.

MODERATOR: Next question.

Q: My question mainly has to do with these colleges that announcing plans to get back back on campus. And I think a lot has been written about the classroom and the class building virus spread threats. But I kind of wonder if we’re paying enough attention to the social aspect of students being back on campus and young people being there. So I guess my question is, the social environment there, the parties, the potentially football tailgates and things like that, is that a top concern for you? And is there any recommendation that you would make for it for students that are planning to go back?

STEPHEN KISSLER: Yes. So that is absolutely a concern. I think that, again, prolonged exposure indoors in classes is one thing, you know, there’s definitely a possibility for spread. But there have been certainly documented cases of parties among college age students that have sort of kicked off local outbreaks in various cities around the US. So that is absolutely a big concern. I don’t see how you can gather people together, especially college students, and and and expect them not to interact socially. I think that’s one of the best things, the social ties that you make is an important part of the university experience, I imagine.

Framing this in terms of the ways in which the virus is most likely to cause large outbreaks is probably the important thing. So it seems to be increasingly clear that super spreading events are very important for sort of kicking off outbreaks. Basically what that means is that one of the best ways that we can mitigate the potential for outbreaks to happen on college campuses is making sure that there’s never an opportunity for someone to pass infection onto large numbers of other people. Now, you can imagine that large gatherings and parties are great venues for super spreading events to occur. And they have happened in the past. So I think that communicating with students about the fact that we’re not asking them to necessarily quarantine in their rooms indefinitely and not see anyone, but thinking about the number of distinct people who they come into contact with over any maybe two week period of time, roughly as long as that number is relatively low, then that reduces the possibility of super spreading events from happening and can really help to mitigate the possibility of large outbreaks happening on campus and in the surrounding community.

So my hope is that that would be the sort of the primary messaging. And then the secondary one would just be staying very on top of just how you’re feeling, taking your temperature regularly. And ideally, if we have cheap tests available, then taking those regularly as well. That’s something I can speak to a little bit later as well. There’s recent studies that suggest that even if the test sensitivity isn’t that great, as long as they’re being done very frequently, they can go a very long way in identifying people who are infected early and preventing them from spreading infection later. So I think all of these things sort of come together to create a scenario in which college campuses are much safer in the fall.

Q: I guess just real quick follow up. Is there a number or range that you would recommend to a student? This is what you should cap your social circle at, this is how many people you should be seeing on a frequent basis?

STEPHEN KISSLER: Yeah, it’s hard to pick out a number. If I were to choose one, it wouldn’t be necessarily evidence based, but just based on sort of rough epidemiological intuitions. But we do know that if you take the average number of people who an infected person will infect, it seems like that number, the reproduction number, is around 3. It does seem like there have been scenarios in which it seems like people are probably infecting substantially more than that. So if I had to pick, I would say that it would be ideal if that number was on the order of 5 to 10, maybe at most, and aim for that as the number that a person would see. But again, that’s more based off of intuition than any sort of sound scientific mathematical evidence I can give.

MODERATOR: Are you all set?

Q: Yeah, just real quick. I did mention it in the first question, but would you recommend having a college football season, or recommend against having a college football season based on the social environment, as well as the threats to the players and coaches?

STEPHEN KISSLER: I don’t think I’ve thought enough about all the implications to know for sure whether I could make a recommendation one way or another. It seems like there are potentially ways to have a sports season relatively safely. But yeah, I think you are right that the peripheral social activities around these things, and especially having large numbers of spectators together at the same time, would be a major risk factor. So I wouldn’t come down and say that. I wouldn’t say that like necessarily sports can’t happen in the fall. But I think that the way that we do them and potentially the peripheral social activities, we’ll have to be very careful and mindful and very clear about our expectations around them. I’m not sure how those sorts of things would be enforced, or what exactly the specific policies would be. But I think you’re on to something really important, that it’s not just the events themselves, but actually the social activities that surround them that will be major risk factors for spread of the fall.

Q: Thank you very much.

MODERATOR: All right. Next question.

Q: I had a question about vaccine production. We’re seeing a lot of companies sign these billion dollar contracts with the government. But who exactly decides when a vaccine has crossed the finish line? And is there any standard that says that this vaccine is safe enough and effective enough to be administered to the public?

STEPHEN KISSLER: Yeah, so, traditionally, I believe that they just go through the same standard licensure of any vaccine and drugs with the various phases of clinical trials where the first is to assess safety, which many of the leading candidates have already done, then effectiveness in a small population. And then finally, effectiveness and safety in a large population, which is sort of what some of the leading vaccines are going through right now. So I’m encouraged by the speed with which some vaccines have showed promising results.

Yeah, you’re right, so I think it’s to my understanding, and I will say upfront that I’m not an expert in vaccine licensure, but it seems like, at least in the United States, that’s that’s up to the FDA. And that’s the body that will decide whether or not it’s safe and effective and able to be given to patients. Until that go ahead happens, that seems to be the key gatekeeper in the dissemination of vaccines.

Q: So as a follow up, given the fact that we’re seeing this record pace for vaccine development, how comfortable are you that the norms for safety and efficacy will be respected and that we won’t rush something into people’s bodies?

STEPHEN KISSLER: Yes. As you mentioned with any drug, there’s absolutely a risk. And there have even been drugs in the past that have been recalled due to downstream rare secondary effects that we found out were not acceptable. What I will say is that a lot of the secondary effects that we see from vaccines come from, not so much the specific pathogen that they’re targeting against, but the platform by which the vaccine works. And we know an awful lot about the platforms that these vaccines are basically variations on to target the coronavirus in particular. Let me say that basically, our assessments of safety are not happening entirely in a vacuum with these vaccines. There are things, basically, prior information that we have about how safe some of these vaccines could be. And while it’s always important to do the tests themselves, and in the trials to try to ensure their safety to the extent that’s possible, the fact that previous vaccines that have used the same platforms do seem to be safe, I think is very encouraging. So I am pretty optimistic about the fact that despite the fact that these trials are going forward relatively quickly, that they’re also being done responsibly. And yeah, I am fairly optimistic about that, actually.

Q: Just one more quick question along those lines. We’ve seen some recent studies that show natural antibodies from people who’ve had COVID already, are not completely effective at producing immunity. So does that make developing a vaccine more difficult if natural antibodies aren’t doing the job very well? Does that have any implications for a vaccine?

STEPHEN KISSLER: I think the question of the extent to which natural infection produces immunity to reinfection is still very much an open one. We have seen that certain titers of particular types of antibodies have declined over time. And that’s something that seems to happen both with known coronaviruses and a lot of other infections as well. And the question is whether as those antibody titers level off. Is that enough to either prevent infection or to reduce the severity of infection? Either of which would be a very good thing. Certainly, if natural infection does not produce a durable immune response, then that suggests that vaccines might not. But it’s also not necessarily the case. We have a lot of ways to enhance the immune response that vaccines produce, even over natural infections at times. And so I don’t think that necessarily the fact that immunity wanes means that vaccines will be ineffective. And also, we’re pretty familiar with different sorts of vaccines that need booster shots, including the flu vaccine that we get every year. So even if we entered a scenario in which we needed a booster shot or something like that for the coronavirus, I think that that’s a paradigm that we’re pretty familiar with. And it’s something that we could adapt to if necessary.

Q: Thank you very much.


MODERATOR: Next question.

Q: Hi, thanks for doing this. I have three totally unrelated sort of random questions.


Q: One is about predictive models going forward. What is your crystal ball saying about the future and as a part of that, are there certain models that you trust more than others or that we should put more faith in than others?

STEPHEN KISSLER: Yeah, I appreciate you letting me respond to these one by one, instead of firing them off at once. So in terms of predictive models. One of the big questions that still remains is the degree to which seasonal variation in transmission is going to affect affect the spread of the coronavirus, basically, are we going to see a major second fall wave? And I don’t think we have any clear answers to that.

There are a number of models that have been produced that they can give sort of short term projections as to the number of cases that could be occurring and different academic institutions have those and various other groups. I actually haven’t been following those particularly closely because it really seems like we’re beginning to get to the point where we’re doing enough testing where we can sort of see how many cases and how many hospitalizations we’re going to have coming downstream. And our reliance on models is still important, certainly, but for these shorter term projections, I think actually, sort of basic epidemiological surveillance is really the key. As we start to see cases beginning to rise, then that’s when we know we sort of have to start responding. So as we’re getting more direct information about what’s happening on the ground, the need for the short term predictive models, I think has lessened a little bit.

But then if we’re looking into the crystal ball ahead into the future, unfortunately, there’s still a lot of uncertainty about that. What I will say is that it does seem that in communities that have a relatively high seroprevalence, so suggests that quite a few people have been exposed and infected with coronavirus, it does seem possible that outbreaks are still possible in many of those communities. In many of the hardest hit areas of Europe, we are still seeing rising case numbers again. And I think that that’s just partly because we’re still far away from the level of population immunity that we need to reduce transmission.

So I think that the possibility of spread increasing in the fall is a likely one. It’s one that we’ve seen with flu pandemics repeatedly. And it seems like this coronavirus spreads in a relatively similar manner to some of those previous flu pandemics. So I think that that’s a likely scenario. But a lot of that just comes from historical experience, actually, rather than mathematical modeling.

Q: Next question is sort of a random personal question, do you have kids in school? And if you do or if you did, would you let them go back to school?

STEPHEN KISSLER: So I do not. But my brother, who is an internal medicine physician, and his wife do have three small kids, and they’ve been thinking about whether or not to send them back to school. The decision that I would recommend to them and that I would probably use if I had children myself, would depend an awful lot on the district and on the circumstances in which that were happening. So to flesh that out a little bit, I think that my priority would be to prioritize in-person classes for younger children before older children, both because it seems like they’re less likely to spread illness and also because in-person instruction also seems to be more important for younger age groups, whereas for older age groups, it’s a little bit easier to do some of the remote type learning.

So my priority, if I had young children, I would probably want them to be in a scenario maybe where they were also only around largely other young children and I wouldn’t really support an entire school going back with K-12 age group sort of all altogether, at the moment. So I think that’s really one of the key things. And then also, the way in which the district is sort of treating the teachers as well, do the teachers have the opportunity to opt out if they don’t feel personally safe? What sorts of support is being given to the students to make sure that the ones who need to do online learning are able to do that? And so I think that all of those things are indicators of the seriousness with which a school or a district is treating the pandemic and the safety of their students and their staff. And so those things would would sort of have to be things that I would assess. And if all of those things were in place, then I think I would feel more comfortable sending young kids back to school. That’s how I would approach the decision.

Q: And the third unrelated question is, I would love to hear your take on the rapid testing. I know Michael Mina has talked about that before. But why don’t we have these rapid tests? What can be done to bring them around faster?

STEPHEN KISSLER: Yeah. So I’m not aware of the sort of technological and licensure area of the tests and which ones are available. But I do think that as far as I can tell, the technology itself exists. So I think that really the barrier right now is sort of the the will to make it happen. And I agree with Dr. Mina about the fact that, based on all of the evidence that I can tell and what we know about this virus, these rapid, cheap tests could be really key for reopening sectors of our economy and particularly, for making schools safe. I think that administering these tests, making them available to students and their families on a daily or maybe three times a week basis, could be hugely important in preventing the transmission of COVID in schools. So that’s actually something that I’m personally trying to do a lot of advocacy around as well, because I really think that could be one of our most important interventions as we come into the fall to prevent large outbreaks from happening.

Q: And who are you advocating with, and what is it going to take to get this done?

STEPHEN KISSLER: It would be best to have you come back and ask me in a week. My plan for the rest of the week is to do more research into this and to figure out where exactly those leverage points are. But basically, the way that I’m planning to approach it is to first understand which tests are available, how expensive they are, what their availability is, and what the supply chain is that makes them available. And if it seems like those things are in place already and the the only thing that that is left is sort of the will to implement them, I plan on calling all of the school districts with which I’m familiar and the representatives of the states that are in charge of these sorts of things, and pestering them as much as I can until I hear sort of what what their plan is for implementing this sort of thing.

Q: Thank you so much, I appreciate it.

MODERATOR: Next question.

Q: Hey, thanks for taking our questions this morning. And last week, we had a large NASCAR race in Bristol, Tennessee. About 22,000 people are estimated to have attended this event, which makes it probably the largest sports gathering the U.S. has seen in months. When that actually happened, the stadium physically distant spectators in the stands, they required masks at all areas of the stadium, except for when fans were at their seats. But when I was outside the stadium, I saw people at souvenir stands that tailgate without masks on. The community is concerned about people coming in from outside the region and bringing more COVID cases to the region. So I want to ask you two questions. One is, do you have any recommendations for people who may have attended this race as in, should they get tested for COVID-19? Should they be monitoring for symptoms? What are some next steps for those people? Secondly, how might public health experts trace the impacts of these kinds of large scale events? Although this happened in Bristol, Tennessee, it’s possible that we’ll see other large gatherings like this in the coming weeks and coming months in other parts of the country. So, again, one, what are next steps for people who attended this kind of event? And two, again, what are the tools public health that experts have to measure the impacts of these kinds of gatherings? Thanks.

STEPHEN KISSLER: Yeah. Thank you. So it does seem like this nests nicely into David’s question from earlier about social gatherings around some of these large events. The events themselves can be high risk, but also the things that people do around them can also be especially high risk. So first, how would individuals respond to have attended this gathering or who are in the nearby community? So I do think at a baseline, certainly monitoring symptoms that can be as simple as, you know, taking your temperature regularly, taking your temperature twice a day and making sure that it’s not increasing too much. And if it does start to increase, think about staying home and just paying close attention. I think that certainly if a person is concerned about exposure, it would make sense to get a test. I know that many cities, for example, after the recent protests, have set up testing facilities for people who attended those. Both for the sake of the people to understand whether or not they might have been infected, but also to conduct some surveillance.

And this gets to your second point. The local community might want to think about allocating some tests and doing some public outreach to try to encourage people who had any contact with that event to get tested, and to see if it led to a rise in cases. So that’s sort of the public health approach that we might take. I think that it’s probably not necessary for everybody who attended to go out and get a test. I mean, again, I’m encouraged by the fact that people were wearing masks probably during the events to a large extent, that it was outdoors, so that reduces the probability of transmission for sure. But, yeah, it’s really difficult to figure out what the overall public health impact of these sorts of events are, just because there is so much randomness in the spread of COVID. You know, one large spreading events that leads to another large spreading event, can really make a big difference. Whereas if a lot of these chains of transmission sort of die out, we might not see a large increase from this event.

Again, from a public health perspective, making sure that testing is available for people who were associated with the event and want to get tested is really important from a policy perspective. And then otherwise, for individuals to monitor their symptoms and to maybe think about reducing the number of people who they’re in contact with over the next couple of weeks, could be very important.

Q: Thank you.

MODERATOR: Next question.

Q: Thanks a lot for taking my question. I have a question about contact tracing. I cover a community that has a very low incidence of COVID-19 now, and has also had a lot of surveillance testing. But I’m wondering now that we’re kind of in a low, is it time to beef up contact tracing? Is it time to make sure that you have the capacity to do surveillance in preparation for what is probably going to be a rise in the fall?

STEPHEN KISSLER: Yes, absolutely. I think that’s exactly the sort of thing that we ought to be doing as cases are low. And that’s the sort of strategy I would recommend from everywhere on a local to a national and international level. Our initial efforts were really to bring cases down to the level where these sorts of things, the contact tracing, testing and tracing was possible. Prior to this, there are just too many cases around, and in many cases there still are, to physically do contact tracing. But if you’re living in a community or are a policymaker in a community where it seems like cases are low enough to begin implementing contact tracing into logistically feasible way, I think that’s probably the most important thing you can do with this time. As far as I can tell, that’s probably the best way to ensure that you can keep cases low for as long as possible, as we enter into the fall.

Q: Do we have enough capacity to do that?

STEPHEN KISSLER: It depends very much on the community, I think. I think that some communities in various parts of the country where where cases are low. So I think probably many communities in the Northeast right now and scattered across the country and other places, as well, are probably at the point where that’s becoming a possibility. But other places where cases are spiking right now, it’s probably not feasible, and we need to focus more on sort of broader societal interventions, which are things we are familiar with, whether that means, shutting down venues where large gatherings can happen indoors for a while until cases come down. So it’s a very community to community specific sort of thing.

MODERATOR: Did you have a follow up to that?

Q: I do. I’m sorry, maybe I wasn’t clear. We have a finite amount of capacity right now. Right now we have cases of low enough that that capacity is enough. I’m thinking of what about the future when we can expect an increase in cases? I think there’s been a lot written about how the public health infrastructure has been underfunded for a long time. And I’m wondering whether more has to be done to prepare for this.

STEPHEN KISSLER: Well, first, I will say, I would absolutely advocate for more funding for public health and surveillance and contact tracing to the extent that it’s possible. I think that the more we can do along those lines, the more prepared we will be for the fall and the more we can, either prevent major outbreaks from happening in communities in the fall, or at least stave them off. Both of which are important things to do. I certainly worry that even in cases where even in even in locations where cases are low right now, we could reach a scenario in which they are again too high for the public health infrastructure to maintain things like contact tracing. I think the most important thing to do right now is to develop a clear plan for when strategies will shift, at what numbers of cases? What sorts of epidemiological data will we be looking at, hospitalizations and deaths and these sorts of things, so that we can make sure that the community knows and is prepared and can prepare for that transition. Because I think that the most likely scenario is that we probably won’t be able to get enough resources to entirely quell outbreaks in the fall, exclusively using testing and tracing.

So we will have to prepare for that eventuality, and many communities of outbreaks sort of spiraling beyond those capabilities. So I think in that context, the most important thing to do is first to expand those capacities as much as possible so that we can stave off that transition into broad scale societal sort of shut downs, things like that. And then also to be very clear with the public about under what circumstances that might happen so that the effects of that can be can be reduced as much as possible.

Q: Thank you very much.

MODERATOR: I have a question that was called into me earlier. Let me just read this for you. This is from Liliya Anisimova from Voice of America Russian edition. She would like to know how deadly is the virus, are there any new studies on the fatality rate and data?

STEPHEN KISSLER: So I admittedly have not been following this especially closely, recently. And that’s partly because our understanding of the fatality rate is so dependent upon certainly, testing, so the number of cases that we know we have in the community and especially the population structure of the community. So it doesn’t seem like there’s there certainly hasn’t been anything recently that has really adjusted my thinking about what the fatality rate of the virus is. We still know that it’s much higher for older people than for younger. I think there’s been a lot of important attention being placed recently on the fact that death is not the only thing that matters and that there seems to potentially be a lot of long term outcomes from coronavirus infection that are also really affecting people’s quality of life across age groups as well. So I think that maybe I take that question and sort of transition it into that, that there’s a lot more attention being brought to that. And I think rightfully so. So, yeah, I think I’ll I’ll probably leave it there for now.

MODERATOR: She goes on to ask, the death rate is relatively steady and doesn’t spike despite the new cases that are rising. What could this mean? For the past month, all the experts were talking about expecting deaths to spike, but it has spiked yet.

STEPHEN KISSLER: It seems to me like this is based on old data, actually. So the fatality rates are actually spiking in Arizona, Florida, Texas, even California, various places where we’ve seen rises in cases. And it’s followed about three to four weeks after we saw the rises in cases, which was right about what we expected. So I think that actually falls pretty well into the expectations.

MODERATOR: And she would also like you to comment, if you can, on the situation, particularly in Florida, which is where she is located. What can be done or should be done? Any prognosis for the state as it’s becoming an epicenter?

STEPHEN KISSLER: Yeah. So, I mean, I think that some of the steps have already been taken, so sort of peeling back some of the reopening measures, closing bars and things like that in various places. Absolutely important. You know, at this point, one thing that I have been encouraged by is that it does seem like the rate of testing that’s been done in Florida has really been increasing a lot lately. And I think that’s very valuable, very important. And continuing that effort will be crucial in identifying which communities are seeing rises in cases. It does seem like the epidemic is fairly heterogeneous geographically across the state. So there are different towns and cities that are being affected at different times. So being able to generate sort of a tailored response that’s sort of more targeted and less disruptive really depends on that kind of widespread testing. So I think that continuing that increasing testing capacity and then just being very clear about messaging that, again, we’re safer at home. Mask wearing is very important. Gatherings, if they happen at all, really ought to be happening outside to the extent that it’s possible. And sort of the basic measures that we know do help reduce the spread of COVID are the things that we ought to be doing with real effort right now in places where cases are continuing to rise, especially in Florida.

MODERATOR: Thank you. Dr. Kissler, do you have any final words before we end the call?

STEPHEN KISSLER: No, that’s all for me. Thanks everyone for your questions.

This concludes the July 22nd press conference.

View more press conferences