Coronavirus (COVID-19): Press Conference with Stephen Kissler, 09/23/20

You’re listening to a press conference from the Harvard T.H. Chan School of Public Health with Stephen Kissler, research fellow in the Department of Immunology and Infectious Diseases. This call was recorded at 11:30 a.m. Eastern Time on Wednesday, September 23rd.


MODERATOR: Dr. Kissler, do you have any opening remarks?

STEPHEN KISSLER: Yeah, just briefly, I recognize that yesterday we passed the important milestone of 200,000 deaths in the US. and I just wanted to note that and to just recognize that we’re still very much in the thick of this. So, I don’t think that there’s much for me to say to set the scene. I’m actually just interested to hear of people’s questions are so, happy to take questions.

MODERATOR: Great. Thank you, Dr. Kissler. All right. Looks like our first question.

Q: Hi. Thanks for doing this. There’s been a lot of talk about what could happen this winter with COVID if cases are going to increase as people spend more time indoors. Can you talk about what you anticipate might happen in terms of cases and deaths? And then what position are we in heading into these colder months? Are we in a good position with cases or are you hoping to be in a better spot?

STEPHEN KISSLER: Yeah, great questions. So, a lot of what we know about the seasonal variation in respiratory pandemic illnesses comes from our experience with flu pandemics. So there’s a little modeling that can be done, too, that can sort of help answer the questions that you mentioned. But again, since COVID is so new, we have to rely on previous flu pandemics and also on what we know about seasonal coronavirus transmission. So, in short, I think that it’s likely that cases will increase in the fall and in the winter, especially due to the factors that you just mentioned, including increased indoor crowding, students going back to school, even a certain amount of fatigue in the control measures that we’ve been trying to uphold over the course of this year. And there may also be some contribution from climate weather or seasonal factors as well. It seems like that’s the case for flu, although it’s unclear to what extent that will be a driver of COVID transmission in the fall. The key thing to note is that based on serological studies, we know that there are still plenty of susceptible people in the population. So we’re very far away, basically everywhere in the country and in fact in the world from reaching a level of unity in the population that would actually be able to tamp down transmission. So I really don’t see a way in which transmission wouldn’t increase somewhat in the fall and winter.

Now, the magnitude of that increase is still unclear for sure. But I think that we can expect it. I would be surprised if things trailed off and went the opposite direction. And so, you know, where cases go, I think that hospitalizations and fatalities go as well. There’s this well formed, sort of well-supported lag between cases and deaths. And part of that is just because it takes a while for people to get sick. Part of it is because it takes a while for infection to spread from sometimes younger age groups who usually dominate the beginning of these new waves of transmission. But nevertheless, I think that those are all things that we can expect as the fall and winter come on. You know, we’ve seen increases in wintertime transmission, both with flu pandemics and then we also know that the seasonal coronaviruses are our wintertime respiratory illnesses. So we’re entering the time of year that’s sort of optimal for the spread of these things for sure. Now, you mentioned, you know, where are we now? And and how does that affect where we’re going over the next couple of months? So definitely in the United States, the picture is very heterogeneous. There are different parts of the country that have done a very good job of suppressing COVID cases. And I think that they’re in a stronger position going into the fall and winter. But that said, I think that the possibility of a rise in in cases is possible just about everywhere. I keep going back to what we know from, for example, the 2009 flu pandemic, where we saw sort of patchy outbreaks of transmission in different U.S. cities in the spring and into the summer a little bit. But then once we have the fall and winter, there is really this unified wave of spread that that basically covered the entire country at more or less the same time. I really want to reiterate that it is not flu. And so it’s transmission patterns, while similar, may have some important differences. But nevertheless, I do expect more transmission in most places in the U.S. and around the world, at least in the northern hemisphere where we’re entering our winter in the coming months.

MODERATOR: Did you have a follow up?

Q: No, that works. Thank you.


MODERATOR: Next question.

Q: Hey, thanks for taking my question, Dr. Kissler. It’s kind of similar to what you were just talking about, although if you’ll allow me to be a little bit more locally focused just for the Miami area, you know, we don’t have the same patterns as the rest of the country when it comes to weather. So I’m not sure how much fall or winter is going to play into what our next few months outlook looks like. You also brought up population immunity or some level of population immunity. You know, I’ve spoken to a lot of your colleagues and done some reporting on that. Here in Miami, by some models, we’ve had a level of spread comparable to New York City area and there might be some explanation there as to why we’re able to bring kind of a really bad outbreak under control. You know, we’ve been on a roller coaster here where we had a terrible June and July and then August kind of calm things down. And now we’re actually at a point here in September where the virus seems to be at a lower level than it was right before the surge. With all that context that my question might have been kind of this long wind up to, is, you know, we’re now at this place in Miami-Dade County where we’re thinking about reopening schools this month or by the end of next month, rather. And I think a lot of people are wondering what potential school reopening has sparked a new outbreak, especially in a hard-hit area like Miami. So I was just curious to get your thoughts on that.

STEPHEN KISSLER: Yeah, that’s great. So with respect to school reopening, we’ve clearly seen outbreaks of COVID in schools and at universities around the country. So anytime you get people who weren’t interacting previously to interact with one another, especially when you do so very suddenly and in large groups, that creates the opportunity for spread and then that spread can spill out into the community. And so, in a way, yes, it’s true that schools can act as hubs of spread as can any other kind of social gathering that we might have. I think the important thing, though, is that it also goes both ways. The best way to keep schools safe is to keep the transmission in the community as low as possible. So certainly, the fact that cases are low right now in Miami I think is important. And it actually gives the schools the best chance of success at both opening the schools themselves safely and preventing those schools from being hubs of spread for the local community. So, you know, there’s really this interaction between the two that I think is important to pay attention to. It’s never really the fault of one or the other. It’s how they interact with one another. And that’s really key.

And briefly, you mentioned the question about your local part of the country and in the end, it’s true. As far as I can tell, we definitely see differences in the timing of certain respiratory illness outbreaks in especially Florida versus the rest of the country. I’m thinking in particular onset of flu season and also especially RSV has very sort of different dynamics in Florida than the rest of the country, which can be partly attributable to the weather there, I think, and also to people’s responses and behavioral responses to that weather. I think the other key thing to keep in mind, too, is that, you know, none of these epidemics are happening in isolation. So if you do see surges of infection in the rest of the country, regardless of what’s happening with the weather and behavior in Florida in particular, you know, people are mixing and that will seed more infections there, regardless of what’s happening in that particular community.

 Q: All right. And just on that note, you know, here in Florida, one week when we had that surge, we saw it really across the state, even though Miami had had a much more intense spring when it kind of took off here in Florida, it took off everywhere, despite differences in the levels of restrictions and behavior. Is there something biological happening there, in your opinion, Dr. Kissler, or how would you explain kind of the fact that when it takes off, it seems to take off everywhere all at once, at least in Florida?  

STEPHEN KISSLER: Right. It depends so much on the geographic scale where you look. It’s like you said, it took off everywhere in Florida, but also the outbreak in Florida was quite different in timing and intensity than even many other southern U.S. states, let alone other places across the country. So as we’re still sort of trying to figure out what governs exactly the variation and timing and severity of outbreaks. That is absolutely a hallmark of this global pandemic so far, is that different geographic regions are hit differently at different times. My rough assessment of the situation basically is that one thing we know about COVID is that it’s frequently spread through super spreading events where one person or a small number of people can infect very large numbers of others. And if you get enough of those happening, you can have these very explosive outbreaks in and sort of geographically contiguous areas. But then if those super spreading events don’t lead to other super spreading events, then that can sort of fizzle out as it spreads outward to some extent. And so I think it really just matters, you know, how many of those are happening in a specific location. And so it has to do with population density and with geographical mixing. I think it’s unlikely that there’s any more of a biological explanation to it than that. But it’s something that we’re going to continue studying for a long time to come.

Q: All right. Thanks so much. I really appreciate your time.


STEPHEN KISSLER: Next question.

Q: Dr. Kissler, good to see you again.

STEPHEN KISSLER: Good to see you. Hear you.

Q: We’ll make it fair. I’ll turn on my video. We have a fourth vaccine now in phase three trial. The Johnson and Johnson vaccine announced it’s going into phase three. I wanted to ask you, there were a couple of things about this, at least in the press release that seemed different. One is that they’re saying it’s a one dose vaccine. You only need one shot instead of another shot, the booster and two, it can be stored at like two to four degrees centigrade. So you don’t need, mass amounts of dry ice near Kelvin temperatures to get it around to different parts of the country. Are these really significant developments? Does this give this vaccine, if it’s successful, a leg up?

STEPHEN KISSLER: In short, yes. And I think that in particular, the fact that it only requires one dose. If we’re just thinking about the U.S., we do have some pretty good ways of keeping vaccines cold. I think that, well, it will probably, basically reduce the cost of the vaccine since it’s sort of more stable at higher temperatures, which is important, absolutely. I think that aspect of it will probably be more important for its international dissemination, which is absolutely important, too. But if we’re taking the U.S. centric focus, I think the thing that’s really exciting to me about that is the one dose, because it’s follow up is just difficult. Any sort of medical follow up is difficult. And if we have an opportunity to induce immunity in one shot, then I think that that’s a huge benefit, especially given the number of people who have suggested that they might not get the vaccine at all. You can imagine that the number of people who might get one, but not two is substantial as well. So that’s the part that I think is most striking to me.

Q: A bigger question. We might have the reflex to think of these vaccine trials as a horse race, and we now have four horses in the race and maybe the first one that gets started is going to have the best chances. Or is it better that we have four horses, or should we have eight? Is that a good analogy, a horse race? Or is that something we should put out of our minds?

STEPHEN KISSLER: I think it’s a good analogy, although I think the spot where the analogy breaks down is that there can only be one winner. I think the fact that we have four in the game is useful for a number of reasons. First of all, like I mentioned, they’re going to have tradeoffs in terms of number of doses, stability at different temperatures, and also their mode of action. It seems like there might be some variation in the extent to which vaccines reduce just symptoms and severe outcomes versus reduced transmission of illness. And so each of those you can imagine being used in different settings, they might also have different efficacy for different age groups. And, you know, we have examples of this with other respiratory vaccines where you use a different vaccine for younger people than for old people. So I think the fact that we have multiple shots on goal here is really valuable. I can see a scenario in which there isn’t a single COVID vaccine, but in which we actually use the benefits of all of these to try to maximize the benefits of vaccination for COVID on the whole.

Q: All right. Thank you very much.

MODERATOR: Next question.

Q: Yeah. Thanks for taking my question. We are sort of looking at Vermont’s testing guidelines and they’ve put out a pretty clear warning against using antigen testing for monitoring asymptomatic people, for doing kind of one-off testing where you’re not doing repeated testing in an institutional setting or that type of thing. And we have had a sort of mysterious and potentially false positives incident here with people who did not actually seem to have COVID, but 64 of whom tested positive. So now, our airport is installing a kind of walk up testing location to run COVID and flu testing antigen tests. And it will be probably mostly used by people coming into the state. You can’t use an antigen test to get out of quarantine per the state’s regulations. But I think it’s going to be mostly marketed to travelers and airport employees. I’m trying to figure out sort of in light of what the state’s recommendations are, whether what kind of ideal usage for the rapid antigen tests currently on the market are and whether this kind of makes sense as a way to kind of do some population monitoring likely of asymptomatic travelers.

STEPHEN KISSLER: Yeah, great questions. So as you said, there’s a lot of different types of testing and sort of like the vaccines question previously, each of them has their own merits and also their own limitations. So antigen testing is useful, particularly in contexts where you need a result quickly. So we can talk about sensitivity and specificity of those tests and which governs the rate of false negatives and false positives, respectively. And all tests, including antigen tests, are imperfect on both of those metrics. Now, the key thing, though, is that the sensitivity and specificity of the tests changes depending on where you are in the course of infection. So while something like a PCR test will be much more able to detect somebody who’s ever had COVID for a long time, even after they’re probably no longer contagious, during the period when you’re contagious, you’re much more likely to test positive. Essentially, the tests are better when you’re most contagious. Kind of makes sense. You’ve got more virus in your system. Your body is mounting a stronger response. And so you’re more likely to be detected by the tests and detect it accurately. So I think the value of the antigen tests in places like airports is that they will be, well, imperfect. They will be able to help screen probably many people who might be coming in and are actively infectious, because if you’re actively infectious, you’ve got a lot of virus in your system and the test will be able to pick that up pretty reliably. And that’s what you want to know, right? If somebody comes in and they test positive on an antigen test, then there’s probably pretty good reason to quarantine, to be especially diligent about that. And so that’s the value that I see. I think, again, we’re going to sort of need all of these different paradigms of testing to figure out how much infection there is in the community. Ideally, you’ll have multiple tests because the tests, the sensitivity of the diagnosis improves as you take more tests. So all of that sort of works together. But I do think that antigen testing, despite the fact that sensitivity and specificity might not be as good as some of the gold standards can still be really valuable for these on the spot decisions and testing that needs to be done.

Q: So the kind of the potential false positives are sort of outweighed here by the ability to possibly pick up a case that might not have been otherwise?

STEPHEN KISSLER: I think so. As far as I can tell, the false positive rate is there, but it doesn’t seem to be high enough to constitute sort of the dangerous people losing faith in the test, basically ignoring a positive when it’s there and then it no longer does its job. But it doesn’t seem to me like we’re quite in that realm yet. It seems like the false positivity rate is still low enough that they’re pretty reliable.

Q: OK, great. Thank you.

MODERATOR: Next question.

Q: Appreciate it Doctor, good to talk to you again. I think we spoke yesterday.

STEPHEN KISSLER: That’s right.

Q: I want to expand just a little bit on, you talked about the vaccine coming out early, phase three trials for the Johnson and Johnson vaccine. We tend to think of a vaccine as a panacea. I mean, you and I have talked about this before, that’s not necessarily true. Talk about the difference between are we gaining in therapeutic treatments as well so that we can make this chronic as opposed to deadly? And is that actually a better hope for the short term than a vaccine would be?

STEPHEN KISSLER: Yes. We’re going to want everything that we have available for sure, but you’re right that improvements and therapies are sort of three different areas, of course. Three different opportunities. We have to intervene. And the way I see that is really managing spreads, managing symptoms and managing immunity. And so for each of those we have testing, we have pharmaceutical treatments and we have vaccines. And so there’s sort of a tradeoff between them where if you have a really effective vaccine that sort of avoids the need for those other things, whereas if you have really effective infection control, that avoids the need for the other things as well. I think that the history of this outbreak has shown that we’re. We can achieve each of those. We’re still sort of waiting on the vaccine. But there are therapies that seem to be helpful for preventing severe illness. We know how to control spread, even though at times we haven’t done the best job of it. And I think that the vaccine outcomes are hopeful. But as you mentioned, they’re not going to be a panacea because they won’t be perfectly effective. Not everybody gets them. And so I do think that there is a lot of room. The point that you make, I think is one that has been and hasn’t received a lot of attention.

But you’re right, I think it is sort of on equal footing with the others, which is if we could have pharmaceutical treatments that reduced the severity of illness, such that getting COVID was no longer that severe of a thing, that would be another really good route sort of out of this pandemic. I am less up to date on what specifically the trials are that are going on for those pharmaceutical treatments, although I know there are a ton. Earlier this year I was really hopeful that we would have a few and might have them relatively quickly. There are steroid treatments for sure that seem to be helpful. But the development of those kinds of treatments has not been quite as rapid or as many breakthroughs as I hoped. Although I think I did have fairly high hopes, potentially unrealistically high hopes for that at the beginning of the of the pandemic. But it’s an area that’s still ongoing. And I think is along with testing, along with vaccines, will continue to be a really crucial part of our response to the pandemic. And it’s something that probably should receive more attention. There’s a lot of scientific and medical attention on it, but I’ve seen less in the media. So I think you’re right to bring it up.

Q: Thank you, Doctor.


MODERATOR: Next question.

Q: Hi. Thanks so much for taking my question. I’m going to ask something that’s fairly specific to Boston University’s current contact tracing policy. So currently, BU defines close contact as someone who was within six feet of an infected person for at least 15 minutes, starting from two days before symptom onset. As a result, BU currently does not require students to identify professors or classmates as close contacts, despite sitting in class with those people, sometimes for close to three hours. My question is this. Based on our current knowledge, if a student who tests positive spends one to three up to four hours in the same in the same room as professors and classmates, should these people be identified as close contacts, regardless of how apart? How far apart students are sitting?

STEPHEN KISSLER: Yeah, I mean, there’s so many tradeoffs here. But I think that to air on the side of safety and I think a very reasonable level of safety, I would say yes. You know, I think we can give a little bit too much credence to the six-foot 15-minute rule. But, of course, as you say, it’s a tradeoff where, you know, if you’re within one foot for five minutes, that’s a very high exposure. And also, if you’re within, you know, maybe 15 feet, but for two, three hours. That’s also a substantial risk for exposure. Of course, there are all sorts of contingencies here where ventilation helps, mask wearing helps, and all of that can reduce sort of the probability that you should be considered a close contact. But I think that definitely, if you’re spending on the order of hours indoors with a person who might be actively infectious, then to me that would constitute close contacts.

Q: Thank you so much. I do also just have a follow up, because recently the CDC published and then retracted an update to their transmission guidelines, saying that airborne transmission might be contributing to the spread of the virus. I’m wondering if that were to be published within the next few weeks, how would be used current policy look in the context of that update?

STEPHEN KISSLER: So my sense is that epidemiologically speaking and in terms of control measures, the update itself doesn’t hugely change our conception of what needs to be done to control of it. So it frankly, it is pretty clear that COVID can spread through airborne aerosolized transmission. But it just really isn’t a question of either or, it’s kind of a both and, where droplet spread is really important and may well be the dominant mode of transmission, despite the fact that airborne transmission can, in fact, occur. And so all of the sort of droplet precautions, measures that we’ve been taking, which include distancing and mask wearing, will remain to be very helpful. And there’s plenty of clear epidemiological evidence that those things are very effective in reducing transmission. So whether or not we classify this thing as an airborne virus or a droplet spread virus is important for sure. But I think that fundamentally it won’t do much other than maybe slightly change the interventions that we already know are effective. As many of the things that I was mentioning and distancing and especially ventilation that even mask wearing can also help prevent the spread of airborne viruses. Maybe not to the same extent as droplet ones. But again, the epidemiological evidence is pretty clear that all of those things are effective in reducing transmission. So I think that regardless of the guidelines, the fact is I think we just sort of need to keep our heads down and keep doing what we know works.

Q: Thank you so much. I appreciate it.


MODERATOR: Next question.

Q: I was a little bit late to this, so forgive me if this has been addressed regarding the transparency of vaccine. And I wonder if, you know, within the structure of the NIH and the FDA oversight and existing authorization or assurance process. Is there a meeting or a mechanism where everyone can see the data? And then I’ve got an easy follow-up question.

STEPHEN KISSLER: Great. So I am probably not the right person to answer that question. I don’t really know the ins and outs of the institutional structure of vaccine development. I do know that if there were a centralized place where people could see sort of the results of vaccine trials in real time, sort of as there in progress, though, that would likely compromise the double blind nature of those trials and could bias the trial administrators towards expecting to see certain outcomes which could compromise the reliability of the trials themselves. So I would be surprised if such a sort of centralized repository was sort of openly accessible to medical and scientific professionals were there just because of that. But I unfortunately can’t say for certain.

Q: Thank you. And then my second question relates to antigen testing. Were those test results reportable, same way that the PCR tests are reportable? And I wonder how we continue getting accurate case counts once we start doing widespread antigen testing?

STEPHEN KISSLER: So at the moment, antigen testing is, to my knowledge, only approved for use with oversight in a clinical care setting. And so in that sense, I believe it is still reportable, although I think the recommendation is to follow those up with a PCR test. Most people get tested twice. So I think that that’s the standard whether or not that’s actually occurring. So yeah, I think that as antigen tests sort of become more widespread and as confidence in them increases sort of as we’re gathering more data, to the extent that they align with PCR tests, I can see us shifting to a scenario where those are playing a larger role in surveillance and understanding the level of prevalence in the community. And I wish I could say this decisively, I’m not actually sure to the extent to which antigen tests are reportable relative to PCR. I think that they are in certain settings. But again, I’d have to speak with a clinician. And I imagine it varies from place to place anyhow. But nevertheless, I think that due to their speed and also because it seems like their accuracy is pretty good, I think that whether or not they are now, they will play a really crucial role in surveillance and clinical diagnostics moving forward.

Q: So would your recommendation then to make these test results referable so we can keep a case count? Or is this just really not practical?

STEPHEN KISSLER: Yeah, I mean, I think that we do lots of reporting. And so I think I think it is practical and I would recommend it, although I would also recommend reporting which platform the test was done on. If we’re just reporting positives and negatives, it can be difficult to compare across platforms and to know for sure how to match up the data. So as long as we’re reporting the outcomes of those tests and reporting that their antigen tests and which tests they are, then I think that absolutely that’s something that ought to be reported. And I think that we have good frameworks for doing that.

Q: Thank you very much.


MODERATOR: It looks like it’s our last question so far. Do you have any final thoughts you’d like to share with us?

STEPHEN KISSLER: No. Just thanks very much for your time, good questions and wish you all the best.

This concludes the September 23rd press conference.

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