Coronavirus (COVID-19): Press Conference with Leonard Marcus, Jack McCarthy, Edward Nardell, and John Spengler, 10/28/20

You’re listening to a press conference from the Harvard T.H. Chan School of Public Health with Leonard Marcus, founding co-director of the National Preparedness Leadership Initiative, a joint program at the Harvard T.H. Chan School of Public Health and the Harvard Kennedy School. And Jack McCarthy, president of Environmental Health and Engineering Inc. And Edward Nardell, professor in the Department of Environmental, Health and Immunology and Infectious Diseases. And John Spengler, the Akira Yamaguchi Professor of Environmental Health and Human Habitation at the Harvard Chan School. This call was recorded at 1:00 p.m. Eastern Time on Wednesday, October 28th.


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

LEONARD MARCUS: Yes. Thank you, Nicole. And thanks to all of you for joining us. The Aviation Public Health Initiative jumped into a difficult set of problems and questions that are facing us now in the midst of this COVID-19 crisis. Many times, people will feel that they’re in a conundrum. Do I stay home? Do I not engage in commerce? Do I stay away in the midst of this pandemic? Or do I go out and go to bars and not be responsible? And we’ve had something of a binary split in this country about how the population is dealing with this COVID-19 problem, and we see how that translates into surges in numbers as this crisis now is only accelerating. Our project wanted to understand how it would be possible to get a middle ground there of being able to continue to engage in somewhat normal activity, commerce, aviation and in the context of all the complexities of COVID-19, we looked at the aviation environment and there’s several important elements about aviation. Number one, it’s a technologically very sophisticated environment. An aircraft, when we think about it and we oftentimes don’t really understand the complexity, it can take us up 35,000 feet into the air. It’s very, very technologically sophisticated with extraordinary engineering, so we wanted to understand that environment. Second thing about aviation is it’s behaviorally controlled. When people get on the plane, they comply with stay in their seats during takeoff and landing. They comply with fastening their seat belt. We’re just used to it. And so, this is a second element about aviation is people follow orders. And the third thing is that to understand what are the qualities of the SARS-CoV-2 novel coronavirus? How does it operate in the aviation environment? And then studying what could be done to allow people to fly and also to reduce the risks of transmission of disease in that unique environment. So that was the question that we faced. We had conversation in the midst of this environment. I co-direct the National Preparedness Leadership Initiative. We are, throughout a crisis, talking with government leaders, business leaders, community humanitarian leaders about their problems in coping with the crisis. We talked with people in the aviation industry. They are interested in working with us on a study of reducing risks in the aviation environment. And we divided that study into two phases. The first phase is the gate to gate. So that’s from the time that you get on the jet bridge, on the plane, and then at your destination. So that was phase one that we looked at in the report that’s now listed on our APHI website. Our second study will be on the curb to curb. So getting to the airport, getting to your gate, what happens in the building, what happens in the conveyances that move people around the airport. That study will be released, according to plan, late December. We have here three of the key scientists who’ve been involved in the study and I will ask each of them for some brief remarks, so you understand what we’ve done, and then open to your questions. So, Jack Spengler, you want to share?

JACK SPENGLER: Yes. Thank you. I think you’ve said it well, when we took on this issue of disease transmission on airplanes and how to mitigate disease transmission. We really took a system view of this. So included in the system are the passengers and their behavior, the crew and how the flight crew manages people’s behaviors, every important aspect of it, what are the procedures the airlines put in place. But think about the aircraft itself. It is a marvelous machine, you said it well, that can give us comfort and good air flow with 35000 feet. We don’t even sense it really for the most part. But the plane is also on the ground at some time. So we really wanted to understand that the plane operates both in the air and when it’s on the ground, when you and I are getting on are getting off those planes and we know that when we travel, perhaps you’re in the back and you know that you might be waiting 20 minutes to get off that plane, depending on how crowded it is. So these are important segments of travel that we looked into, as well as the sophistication of the COVID virus itself is a challenging proposition. And Ed could say more about that.

LEONARD MARCUS: OK. And Jack McCarthy, if you want to speak a little bit to the modeling that we had done.

JACK MCCARTHY: Sure. Thanks. One of the things that we wanted to do here, and just follow up on what Jack was saying, is really take a systems view. And to do that, you really have to understand all the interrelated pieces that occur on an aircraft. And it has to do with not only the equipment that you have, with respect to the ventilation systems and the filtration systems you have in the air exchange rates that occur, but then also the positioning of people and where they’re seated and when they’re up and moving about. And again, all elements of the trip. So we looked at and reviewed all the models that have been published historically, as well as models that have been developed by Boeing in the Airbus and to review what they did. We also looked at data that was collected by the U.S. Transcom through a Department of Defense contract that they had to look at actual data being collected. Very sophisticated set of sampling protocols being followed, ideographed, to validate the models. And then independently, we developed our own model to then see how, in fact, that would compare, because we felt confident in our ability to look at different aspects of the trip. And the thing we did find is that there was a confluence of all of this data. So there’s consistency. Numbers may not be exactly the same, but there’s strong consistency in the overall magnitude of what we have. And that gives us confidence in the overall system and that the ability to understand what’s happening on aircraft right now.

LEONARD MARCUS: Great. Thank you, Jack. And Ed Nardell, if we could just get your perch in this study.

EDWARD NARDELL: All right. So as a physician, I’ve been interested in the inner space between infectious diseases and the built environment for many, many years, mostly coming from a tuberculosis and influenza perspective. And so with SARS-CoV-2, the issue is how is it transmitted when in the course of infection, is it infectious? And what kind of interventions make a difference to mask wearing? Of course. And the ventilation in particular in this setting. So I think that understanding of the disease is critical to this project as well.

LEONARD MARCUS: Thank you. So at this time, we’re open to any questions you might have about the modeling, about the study, about the disease itself and Nicole you can start, I guess, if people have questions.

MODERATOR: OK. First question.

Q: Thank you so much for doing this. I’m not sure which of you this question would before, but I’ll let you decide that bit. I quickly glanced through the report. It seems as if one of the recommendations is not to have reduced capacity, sort of like you’re doing in restaurants like 25 percent or 50 percent capacity. Am I right about that? That that’s not a recommendation? And along the same lines, I’ve heard before that each set of HEPA filters is designed to handle like one row or two rows, I’m not sure. What are they designed to handle? Like how many how many separate little units of filtration are there?

LEONARD MARCUS: Dr. Spengler, would you speak both to the modeling of the individual seats as well as the HEPA filters?

JACK SPENGLER: Yeah, so I’ve taken a reverse. I’ve been in the belly of triple sevens and dream liners when I was out at Boeing for an FAA project we were funded to do. They have banks of filters and it covers all the air. So you have fresh air coming in, compressed off the engine. Dreamliner actually takes it not off the engine, but right from the air stream itself. But that’s at low pressure. So you have to compress it. You have to condition it and add heat or or cool it down depending on what the environmental requirements are. And half of that air comes in as fresh air and half is coming back to us through filtration. So it typically is a mixture of fresh air and then well filtered air. And the HEPA filters are for the entire plane. So that I think is an important part. The other important issue is that through the engineering, they’re trying to design and balance the flow across the whole cabin so there’s not much longitudinal movement of the air. It’s mixed and taken out at our feet. And so it comes in above us mixes and down and exits the plane through collection at our feet along the walls. So that’s the basic design. In the report, we have schematics and diagrams and hopefully do a better job of explaining this. So that’s on the filtration side. And Jack, you can handle how the modeling looked at all sorts of seating configurations.

JACK MCCARTHY: Sure. And just to elaborate, as Jack said, the air’s coming, being delivered to the top of essentially each row and then is circulating around and being exhausted at the feet. And what that does is it really localizes the flow, so it’s not being moved to any significant distance throughout the entire aircraft. And so we looked at a number of different configurations where we had a potential infectious person sitting in each thing, whether that be at the window, the middle seat or the aisle seat, and didn’t see any meaningful difference at all between potential risk. So we find that in each one of these seating configurations, there is a very, very low risk of a potential infection dose occurring. And that was actually confirmed by the monitoring study that was done by the Transcom, where they actually released particles into the air stream and then looked at how these particles would be distributed throughout the cabin. And they found that they agreed very, very well with our model. So along those lines, you would not think of restricting seating anywhere within the aircraft or limit the number of people because of the very, very high air exchange rate. The air is being exchanged 20 to 30 times per hour. And so that means that you have a residence time of about two to three minutes within the space. So, again, a very high turnover of air within the cabin.

LEONARD MARCUS: Dr. Nardell, could you talk a little bit just about the varions, the droplets, the aerosol quality?

EDWARD NARDELL: Sure. As I think everybody knows, there has been some controversy over exactly how SARS-CoV-2 is spread. The originally thought to be large droplets and contaminating surfaces and also potentially directed from one person to another. And then there’s the small droplets which can remain suspended in air. Now, the key thing I think, in our report is that all of these pathways are addressed by layers of interventions. And so, for example, wearing the mask is absolutely essential to stop the large droplets, which it does very effectively, from contaminating surfaces and from directly impacting on other passengers. The small droplets, many of which escape the surgical mask, are handled by this incredibly rapid clearance around the source so that they don’t have a chance to spread within the airplane and they’re immediately exhausted down below. So I think it’s absolutely key, the message we want to give is not that the airplane mechanical system alone is sufficient, but rather that the combination of behavior, wearing a mask, minimizing the time that mask is off, any kind of eating or drinking, and then also depending on the on the airflow of the airplane, to minimize anything that escapes the mask.


MODERATOR: Really quick. I had a question. I was wondering if the Transcom study is the Department of Defense study that was released a few weeks ago. Is that correct?

LEONARD MARCUS: Yes. Jack, I don’t know if you want to speak to this.

JACK SPENGLER: I think that’s well said. We actually had long discussions with the investigators themselves. We didn’t want to rely just on the report and what was published through some interpretation. So we talked to the ones who actually did the experiments. And this was important to us to really understand the context in which these experiments were done. And so we could better interpret the results. And let me just underscore, what it demonstrated is that it’s not just sufficient to run the ventilations system on high performance during the cruise. It can be done. It should be done when it’s on the ground. And that’s not always been the case. And maybe that’s OK. When we didn’t have pandemics or when it wasn’t flu season. All right. We’re not on there that long. And maybe they airflows can be reduced. But I think we’ve seen not only our report, but many other reports independently say, this now is a different time. This is pandemic time. And we must ensure that these ventilation systems and the mask wearing, and then physical distancing, onboarding and deep deplaning are all in place to keep us safe.

LEONARD MARCUS: Just to underline what Jack said. We interacted with the people who did the Transcom study. There was another Department of Homeland Security Science and Technology study. We had a briefing with them, so we had to go back and forth with the people at Boeing and Airbus. We’ve met with the administrators of the FAA and TSA, we’ve been speaking to people at the CDC so that our approach is to be interacting with these people, asking questions, giving them an opportunity to interact with us. So as Jack Spengler earlier said, this is a comprehensive study. That’s what we meant. We engaged with all of these other people.

MODERATOR: Are you all set?

Q: I’m not trying to be greedy, but I had one very quick follow up. But simply, I noticed in there that you said that if you do all there’s layering of prevention, your overall risk is relatively lower even than going to the grocery store. And I was just wondering, does that mean assuming a similar number of minutes, like are we saying an hour flight versus an hour in the grocery store or is it not that specific?

LEONARD MARCUS: Jack Spengler, do you want to take that?

JACK SPENGLER: So, you know, there’s lots of ways of comparing these things and there are many activities that I’m engaged in, we’re all engaged in, and we do it with caution now and we get on with our lives the best we can. But what we’re saying is that these three protective layers, four really, disinfection, behavior, distancing when you can, masking always except when you have to drink, and the ventilation systems in high-performance, all of those things are protective. And the modeling says are protective over long durations, out to many, many hours of flight times, because some flights are 10 hours, 15 hours. So we wanted to make sure that all of these things had a long endurance, let’s say, as preventive measures, and that’s what we were demonstrating.

Q: All right. Thank you.

JACK SPENGLER: Tom, you can look at Chapter 10. We lay this out in some tables, 10.2, 10.3, as we felt it was a good way to express what it meant for how long before you would might see a secondary infection with masking, without masking, different ventilations rate, different production rates of viral shedding. So we really tried to do a bracketing of possible conditions.

LEONARD MARCUS: Do you want to jump in on that infectivity as well?

EDWARD NARDELL: On the infectivity. Well, you know, among the things we don’t know at the moment is if there is an infectious dose, we don’t know exactly what that is. But I would say that the evidence so far suggests that on airplanes there have been relatively few incidents that are suspicious for transmission during flights. There’s been a number of reports of people who have ended up on planes with SARS-CoV-2 infection, COVID-19. But whether or not that transmission occurred on the plane is by large questionable. It certainly could happen and will happen. But we think not very often. And that suggests that the dose in most cases is a substantial one. And that rapid clearance of these particles from the breathing zone is effective in preventing transmission.

LEONARD MARCUS: And Jack McCarthy, if you could just speak to the difference between the plane, the grocery store, the restaurant.

JACK MCCARTHY: Yeah, I mean, these are different environments and different potential exposures. And as we’ve talked about throughout this call, really has been the layering effect of utilizing multiple approaches to helping control potential risk. And when you’re in these different environments, you can have people who may be infectious that may be in grocery stores. And if they weren’t wearing their mask, they’re wearing them improperly. They could be releasing viral particles and shedding virus particles. It’s going to get diluted down within the large volume that you have, and the risk is relatively low. But we see that same risk being translated to the time spent in aircraft. The difference that you find in restaurants, and that’s actually where a lot of infections are starting to occur right now, is because people aren’t wearing their masks regularly. You have people who may be asymptomatic that are going to be in very close proximity to colleagues and friends there, that could be shedding particles. And that’s really where you see a lot of these infections occurring. That and spending time in bar areas and things along those lines. So, you know, if you really want to take into account the overall environment as well as these different layers of protection that you can utilize. And that’s what we found with aircraft, is that it can be very, very effective if these layers are utilized.

LEONARD MARCUS: One thing among the many people we spoke to were flight attendants, as you probably have heard the airlines right now. No question. You’re going to wear your mask. And if someone is not properly wearing their mask or takes their mask off for too long, a flight attendant will politely go up and ask them to put their mask on. Will do it a second time, third time, the passenger is on a no-fly list until COVID-19 is over. So one of the other unique elements of the aviation industry being an airplane is the compliance that we talked about of wearing your seat belts and keeping seated during takeoff and landing, likewise, has translated into requirements regarding mask wearing on planes. And that, as Dr. Nardell said just a moment ago, also contributes to a significant difference in this environment.

MODERATOR:  Hi, this is Nicole, really quick, we have several more reporters with questions. So I’m going to ask that the responses be a bit briefer so we can get to everybody. All right. I think, Tom, you’re all set. Next question.

Q: Hey. Thank you. If I can ask two questions. One, when you were talking about the modeling studies, when Jack McCarthy was, you’re saying that the risk is low. And I’m wondering, like if we write about such modeling studies, what are kind of the key caveats or assumptions these modeling studies make? Like, you know, how many people are these modeling studies assuming are infected on the plane? Is everyone wearing a mask? Are we doing drink service? I guess my question is, in what instances might these modeling studies not, you know, help us.  In what ways may they break down and what caveats are there? And then my second question is, I think we’re at a point where different airlines are doing different things in terms of seating, in terms of like their precautions. And I’m wondering if you all think there are like a list of things that, you know, if I’m a passenger on an airplane, I want to know the airline is doing X, Y and Z if we have that list and we can hold them accountable?

LEONARD MARCUS: Jack Spengler, do you want to do the first question?

JACK SPENGLER: Jack, I think it was directed to you. I would be glad to do it. I was making some notes on some of these other issues that you mentioned there. Thanks for your question. It’s right on. I mean, models are approximations, you really have to understand.

JACK MCCARTHY: Yes. I agree with Jack. Models are approximations and it’s good to understand where exceptions may exist. And what these models were actually intended to do, were to look at people that are seated, that they’re oriented looking forward. There is one person that was infected in that individual be moved around in two different locations to try to look at this potential spread in the adjacent seats, as well as what was happening in the rows in front and behind. So you’re basically looking at a five-row block around there. And so having that one person would be would be important. And that was what was replicated in the Transcom studies as well. They looked at people with masks on, masks off. And as you might expect, with the masks off, people would have a potentially higher exposure. You still had very high air exchange rates, but nevertheless, you will have higher potential exposure. So that kind of goes back to some behavioral issues where you want to have people wearing the masks, not take them off for prolonged periods of time, and taking 45 minutes to drink a cup of coffee. But we want to be able to have people be smart about if other people have their masks off while they are eating, you may want to keep your’s on. And again, I think its people being respectful of the people within their group. So, you know, I think there are certain limitations. But overall, as I said earlier, there is consistency throughout and gives us confidence with respect to the fact that the risks are really quite low while you’re on the aircraft.

LEONARD MARCUS: And to the second question you asked about the differences in the airlines. We started our conversations with them in May and over this period, we find that they’re coming closer and closer together so that they all have very strict face mask policies. They’re all being very careful about disinfecting the planes on turns and overnight. We made a recommendation that ventilation systems be kept on when the plane is on the ground. And if there’s variation, it would be there. We weren’t here to make business decisions for them. That’s their province, obviously. And we were just making recommendations about ventilation systems. And that is our recommendation on that score.

JACK SPENGLER: And Ed wants to say something.


EDWARD NARDELL: You know, I think one of the weak links that we’ve been talking about is the boarding and dismemberment of the plane, where probably there’s variable order and enforcement of that order. And that’s going to be an important thing, that people are not ganged up waiting on the bridge or standing in the aisles for a long period of time. And that’s a combination of passenger behavior and airline policies and procedures.

JACK SPENGLER: And you’re right to point that out Ed, because that is the most difficult activity to model, where people are moving, there’s airflow coming down over the middle of the aisle. Someone’s above another person sitting. That’s why exactly what you said, if we get some distancing and air and discharge a couple rows at a time, you avoid that condition.

MODERATOR: Do you have a follow up question?

Q: The big study that we all seem to be referencing, the one that was done by the DOD, I know some conversations I’ve had with people they all warn me, like, this was sponsored by the airline industry and who obviously have an interest in reporters saying that it’s OK to fly. Do we trust this, the work they’ve done, do we feel good about it?

JACK SPENGLER: So I believe the Transcom study was first a DARPA study, and then it’s the air command that are used for expats coming back. They use the same service to bring back people from other countries, China and elsewhere, during the beginning of this. But more importantly, it’s what they used to send troops around the world. So I think this was a real serious attempt to protect the armed forces, first and foremost, they wanted to know if we are sending our military out on these flights, they don’t have undue risk. So that was why DARPA, and I believe Jack and others, that’s why they got into this in the first place. But it has obvious applications to commercial travel. And that’s why it’s a useful study.

EDWARD NARDELL: In addition, several of the other studies are a confirmatory. The modeling is pretty much the same as these particle release studies have.

MODERATOR: Next question.

Q: Hello there. How are you? You all sort of address this question a bit, but if you could say whether or not you will agree with industry executives who say that your study and others show there’s virtually no risk of contracting COVID-19 on airplanes given the airflow system and mask requirements.

LEONARD MARCUS: Thank you for that question. Nice to hear from you. And we do not say no risk. You can’t say no risk until COVID is behind us. There is always some element of risk when we’re still in the middle of the pandemic. And so what you’ll see that we say in our study is low risk, not no risk. And what the challenge and the puzzle for public health in general is right now, is what can we all be doing to reduce risks while still engaging in some element or some aspects of a normal behavior, so we’re very clear. It’s reducing the risk, but there can’t be something as no risk until we have a vaccine and until this is behind us. And Ed, I don’t know if you want to speak to that as well.

EDWARD NARDELL: No, I agree. I think there is no complete safety. Again, there’s so many steps we’re going to address, the getting to and from the airport in the next report where there are, you know, perhaps greater risks than being on the airplane. I rode the Boston T today, two directions. It’s not risks free. It’s probably also low risk. But, you know, there’s no risk-free travel or activities in the middle of a pandemic, as Lenny said.

Q: So to clarify now, these are just extremely low or virtually no, but not, you know, zero. Hey, just a quick follow up. Are you all saying, and sorry if I missed this in someone’s earlier comments, but you’re also saying that there’s no more risk of infection if there’s an empty seat between you and infected passenger or not? So does it matter at all if the middle seat is open or no? Is there any affect or change in risk given that distance?

JACK MCCARTHY: Yeah. When you actually look at the data that has been collected, you cannot see any measurable difference in the risk with the middle seat being open or the adjacent seat being vacant versus where someone, an infectious person may be seated. You know, of course, with some additional distance, you would expect that there could be some slight reduction. But it’s really not measurable because of the very rapid airflow you have and how quickly material is migrating through. And as we mentioned earlier, having the masking is critically important because that’s really one of the very first barriers that you have that eliminates the large droplets that may create infectious surfaces that are there because it is acting as a barrier. It’s also very effective in reducing the aerosol particles that may be released. So, again, I’m not saying it’s not going to be different, but it’s not measurable with the way that things have been analyzed right now.

EDWARD NARDELL: I think one of the areas of confusion may be that we talked about six feet on the ground, more or less, and that in rooms where there is relatively two, three, four air changes in most circumstances. But here we’re talking 20 air changes. So that changes the whole situation of particle residence time dramatically. So, you know, 6 inches or 16 inches or 20 inches doesn’t make much difference when you have that kind of airflow. Same as Jack just said.

MODERATOR: Are you all set?

Q: Yeah. Thanks.

MODERATOR: Great. Next question.

Q: Yes, I’m sorry. I’m actually wondering if you comment. I mean, there’s been a call from some of the unions for a mandatory federal policy for masks. And given sort of the conclusive evidence that masks do eliminate these large droplets, I’m wondering if you would if you would weigh in on that.  

LEONARD MARCUS: We found in our analysis of literature and in our research and the modeling, that people wearing masks will make a very significant difference in transmission of this disease. We certainly examined that in the context of the aircraft environment, and we believe that that would make a significant difference in other environments as well.

EDWARD NARDELL: We also talked to airline attendants who find it very stressful to be the enforcers. And we didn’t recommend this, but from their perspective, we heard that they would love to have some regulations.

MODERATOR: Are you all set?

Q: Yes, I am. Thank you.

MODERATOR: Next question.

Q: I wanted to ask if you have talked to the airlines about any of these recommendations, the new recommendations that you’re making, especially around deplaning and boarding. And what kind of feedback, do you have a sense if they’re willing to do that and is cost an issue?

LEONARD MARCUS: We have spoken with the airline industry about this. They are hearing us loud and clear. There are discussions about it. Again, their decisions are up to them. And they have acknowledged hearing the recommendations and they are talking and considering. What their decisions are is really up to them. It’s not our business, so to speak, we’re research academics, but they certainly have heard this loud and clear.

Q: The other thing I was curious to know what you think about is that there was the pilot for American Airlines who wanted to remain anonymous, but spoke out about pilots in the cockpits, not wearing masks. And then he also went on to say that some of the cleaning crews that come through the planes are not wearing masks. He’s seen it and has asked them to wear masks. So those other variables, I would think, can potentially lead contamination.

LEONARD MARCUS: Jack Spengler, do you want to speak to that?

JACK SPENGLER: Well, I think you’re absolutely right. I don’t think there’s any exceptions that we would provide here. Maybe some very young kid that, you know, even World Health Organization says two to five years old, maybe you can’t get them to wear a mask, but a cleaning crew. Absolutely they should. Pilots, yes, unless it interferes with communication, which is critical. I will say, though, that the cockpit gets a much higher air exchange rate than even the cabin. And it’s not recirculated for them. They get full fresh air. They understand the systems properly. Different models might have different configurations. And that’s for safety reasons. Should there be smoke in the cockpit? It’s cleared extremely rapidly under those circumstances. So we did not assess the cockpit environment. And because it was about passenger travel, that was our focus.

Q: Thank you.

MODERATOR: Next question.

Q: Hi there. So my question is about the efficacy of testing and the importance of testing. Some airlines have rolled out, you know, health pass systems and things where you can upload test results within 72 hours of your flight and things like that. And I think over the summer, some spoke during a House panel and mentioned that one of the only ways to really prevent transmission on board flights would be to do rapid testing of everyone before they board. And I was wondering your thoughts there as to, you know, how testing fits into all the other parameters you’ve been looking at?

LEONARD MARCUS: Ed, do you want to take this?

EDWARD NARDELL: Sure. Well, as you know, testing is only so good. You could test negative and still be infectious. There’s a failure rate of the test, et cetera. But I think that what we’ve really been talking about is that to the best of our knowledge, all of these modeling and the Transcom study. Presuppose that there are infectious people on the plane and it even with an infectious person on the plane, that the risk is very low. If you can screen people out more effectively, the risk would be lower yet. But there comes a point of diminishing returns. Should everybody have to have a negative test before getting on a plane? Probably not feasible at the moment with current testing capability and turnaround. But we didn’t make that recommendation.

LEONARD MARCUS: Jack Spengler, do you want to speak to that?

JACK SPENGLER: Yes, some testing does play a role. We’re going to be looking at the new technologies in our next phase of reporting on that side of things. But I do note that some of the airlines that are already implemented, testing of their flight crew, that their home bases were in, let’s say, highly infectious hot zones that have changed over time from New York to other places. But they wanted to make sure the crew was safe. That was a really important factor because the crew sit next to each other, too, and they interact. So this became an occupational health and safety issue that they were doing. And now we’ve seen some airlines to start to offer testing at the airport. And this is a real advantage because saying you’re flying from the states to Hawaii, in Hawaii it’s strict quarantine requirements that if you test negative getting on the plane, you do it again in 72 hours, which I think it’s a typical time that they say, you can cut down your quarantine time and then you can enjoy your vacation. So testing does play a role. Ultimately, this vaccine, testing, I think, has been real rigorous testing. And there’s a protocol that has to be developed to, as Ed said, make sure we’re not having false negatives that we should wish we had detected.

LEONARD MARCUS: Jack McCarthy, do you want to speak to that as well?

JACK MCCARTHY: Yeah, I would just say that there are a number of different testing procedures that are being evaluated right now to try to minimize false negatives. And as we’re gaining more knowledge and more information, as well as having rapid tests coming into play here, you’re going to be seeing some testing protocols that will likely be occurring 72 hours before you leave and maybe some follow up at the airport. That’s going to dramatically reduce the risk. And you’re talking about orders of magnitude reduction. So I think testing will, until an effective vaccine is available, we’re going to be striving to get improvements in testing in order to have that reduce the potential risk.

EDWARD NARDELL: The other area where testing helps is for the short periods, we hope, where people have their masks off.

Q: Quick follow up, actually, on the point you just made, about what periods when people have their masks off? I was just wondering, you know, what extent that the work you did in other models, studies, you looked at, if there was any sort of analysis of the duration, how much clearer transmission is for the length of duration when someone has their mask off. I’m thinking of, like when we’re looking at, trans-Atlantic trans-Pacific flights coming back, things like that. Folks during mealtimes would certainly have their masks off for an extended period of time. So I was wondering kind of what the threshold is there?


EDWARD NARDELL: Well, I should say the airlines have modeled and we’d modeled masks on, masks off. And it’s pretty proportional. The risk is proportional to the time that the mask would be off. I can’t give you a threshold number, but our report says that mask removal should be minimal. And you do bring up the difficult problem of very long flights where people will be eating meals, et cetera. And my own feeling is that if somebody is eating next to me, I probably will wear my mask and try to eat at a different time. And they’ll be wearing their masks. But that may be more orchestration that is feasible on most flights. But that is a weak link in the system.

Q: Thank you.

MODERATOR: Next question.

Q: Thanks. I know that there isn’t a lot of evidence that there is COVID-19 spread through physical services, but a lot of airlines have gone ahead with excessive cleaning and disinfectant sprays anyways. Is there any evidence that these efforts are helpful or contribute at all to the slow of the spread of the virus among passengers?


JACK MCCARTHY: Sure. The amount of surface contamination is relatively low. However, I think what’s important here is that airlines are taking a proactive step here in order to ensure that it is going to be minimal. They have not backed off of the application of these different cleaning techniques. And I think that’s important until people have a lot of confidence that surface contamination is not going to be a problem. You find that even in health care settings, with the routine cleaning that’s being performed, the potential risk of service contamination is low. You still want to take precautions because you’re going to utilize some very heavily used items, such as the door to the lavatory and things on those lines. You want to take precautions because you want to minimize any potential risks that you have there. So I think it’s prudent. I think the cleaning that the airlines are undertaking, the procedures that they’re utilizing are quite effective. We’ve seen tests that have shown that to be quite effective. And, you know, I think it’s just a prudent approach to take right now because we’re still learning about this virus and transmission and we don’t want to have any surprises coming at us.

MODERATOR: Do you have a follow up?

Q: No, that’s it.

MODERATOR: Great. Next question.

Q: I want to apologize because I don’t know if someone has already asked this. I just wanted to confirm that this study, is it separate from the Defense Department study released a few weeks ago or a new analysis of it?

LEONARD MARCUS: This is a different study. And our only relation to that is that they did a briefing for us about what they found. But we were on separate tracks joining the data collection, the study.

MODERATOR: Do you have a follow up?

Q: No. Thank you so much.

MODERATOR: Great. Next question.

Q: Hey, thanks for taking another question for me. I just want to follow up on something that I want to think through a little bit better and more clearly. So I understand that the modeling is telling us that whether you have that middle seat filled or not is not going to make a difference. But then also understanding that the modeling is kind of based on ideal conditions. You don’t always know who you’re going to sit next to. I wonder if filling that middle seat exposes people to dangers that aren’t easily captured scientifically. Like, you know, some people aren’t wearing masks because of reasons they have, or some people might be a little more obnoxious when they’re eating or yelling. And I wonder if just like having those planes filled kind of exposes, yes, ideally, middle seat filled. No problem. But, you know, we might not get ideal situations.

LEONARD MARCUS: Jack Spengler, do you want to start with that?

JACK SPENGLER: So you touch on a good point. I think on one aspect, if you lighten the load of a plane by not filling a middle seat, the whole probability of an infectious person gets reduced by that much too, in the population. Asymptomatic person in the population who doesn’t know that real happens to get on. Well, you cut that probability. I mean, there’s an advantage to that for sure. You know, whether you’re in a middle seat or not with an obnoxious person next to you or vice versa, you know, this is behavioral. These are the conditions that we all have to tolerate in society and in the discussions with the airlines and the flight attendants. They’re finding very high compliance. People are sitting there, they’re quiet, they’re not boisterous. And if they are, they’re there to back up and change that behavior. So there is something that you can do to control that local situation. And you can even ask to be moved if you want. So how you deal with that situation you described, I think there are alternatives to it, but unless someone does something really obnoxious, take off the mask and really be infectious and cough on you. You know, those situations are impossible to say how frequent that would ever happen. But our modeling actually looks at all the different seat configurations. And the Transcom did too in the other modeling. And look at this variation across those rows and front back and determine that the spatial variation, even though you could pick up small differences, still the ventilation from top to floor conveys the mass of material away from you. So was there some extraordinary bad behavior? It should not make a difference. Sort of a clumsy way of answering your question.

LEONARD MARCUS: And we did speak to the airlines and flight attendants about this. There are circumstances where if someone is really out of bounds, where they’ve actually turned the plane around. And then other times, different airlines handle this differently. Some of them will give you a yellow slip right at your seat. You’re not going to fly again. Others don’t want the confrontation in the air. So after you’ve left the flight, they take note, you know, 12D, and you will be notified that you’re not going to be able to make reservations on that airline until COVID-19 is over. So they’re taking it really seriously. And words getting around.

JACK SPENGLER: Yeah, this is a good point you make because, you know, it’s always the outlier. It’s always the bad behavior that gives the rest of population risk, and under these circumstances. And we heard at least one airline’s I don’t know if they’re all turning this way, but they really train their flight attendants to assess the population, the passengers as they board to make sure they’re interacting with them. And if they find someone being resistant. And they say they’ve done this on a number of occasions. Call the pilot, turn the plane around before it takes off and discharge that passenger. And you do that a couple of times and then the word gets around. They take this seriously. But this has to do exactly what Lenny said. You don’t want the confrontation to be in the air. You don’t have to move people around if you don’t have to. So they really tried to address the outlier early on.

Q: Yeah, I guess I just want to be clear on where if I’m writing about this, where I should express, like, we don’t know everything. And I wonder, you know, for all of you, what aspects of this story would you want to project that? Would you want to say like, well, we don’t exactly know X or we don’t exactly know this? You know, just to be good on that as well.

JACK SPENGLER: I’d like to have Ed chime in on this but, you know, there are some good studies going that show differences in the amount of material that might be shed from people doing different things.

EDWARD NARDELL: So where are the where are the gray zones, I guess? And we’ve mentioned several of them. People walking up and down the aisle can disrupt the wonderful airflow that we have described. Passengers standing in the aisle to get on and off can disrupt that. That’s another difficult part. Taking masks off for prolonged eating and drinking. If people did, that would also change that circumstance. One of the reports of likely transmission on an airplane occurred before mask wearing was required. And just to point out that all these systems can be defeated if people are not wearing masks.

JACK MCCARTHY: I just want to add one thing to what Ed just said. You know, people walking up and down the aisles disrupting air flow, it actually reestablishes itself very quickly. So it’s not that someone walks down the aisle and all of a sudden everything becomes problematic. But I do think it is those gray areas. The biggest challenges are going to be when you’re boarding and then deplaning because of the fact that you many people start to mass together. And that’s really where we think some potential risks could be. And I think that we as individuals, we have some control over what’s going on there because we’ll be able to restrain ourselves somewhat and not get naturally caught in the crush. But I think it also would be perfectly fine to turn around and ask people, you know, to back off a bit. You know, we may have to take some more personal responsibility and try to control what we can about our environment as well.

LEONARD MARCUS: Yeah, I’m not sure exactly what you’re looking for. But if you want a point of controversy, what we’re saying is if we could have all of society to be as compliant with mask wearing as what we have in the aircraft environments. Jack Spangler just mentioned where they take it very seriously. And if you don’t comply, you don’t fly. If we get that in all of society, we would see the numbers and the surge very, very different. So that is a very, very strong message that we’re sending now.

Q: You know, not looking for controversy, I just want to be honest about what we don’t know very well.

MODERATOR: OK, great. Next question.

Q: Thanks. We’re heading into the flu and cold season where we’re going to start seeing some more normal coughing, sneezed, musing, blowing noses. Does this add any risk if you’re on an airplane and people are maybe doing things that might project their air droplets out?

EDWARD NARDELL: Yeah. So that’s interesting. I mean, so I think what you’re asking is if you’re coughing or sneezing for other reasons, does that make it more dangerous for COVID? And I guess it would, except for the systems that we’ve described seem to be able to handle fairly large numbers of infectious particles. In fact, you know, we all have the impression that air travel has been associated with common colds, etc.. We may see that we actually get a reduction in some of those because of all the precautions we’re taking that are effective, by and large, against most respiratory infections, whether they’re spread by direct contact, large droplets or small droplets. All of them are being addressed in the procedures that we’ve described.

JACK MCCARTHY: I’ll just add one thing there. This recent study came out from Australia that showed the number of deaths associated with the common flu because they’re coming out of the winter season now, has been dramatically reduced. And we’re seeing that across many Southern Hemisphere countries right now. So the steps that are being taken as far as being able to increase this infection, increase masking and minimize some of the social interaction, is having very strong ramifications across all of the different infectious diseases that we could be exposed to.

MODERATOR: Are you all set?

Q: Yeah, that’s great.

MODERATOR: OK. Next question.

Q: Hi. A question about deicing. I don’t know if you all addressed this in the report or have any information about it. In my experience, the pilots generally, if I recall, turn off the airflow system when a plane’s being de-iced for whatever amount of time. And I feel like I’ve been in a plane waiting for a half hour or whatever for this process to go forward because they turn off the air to keep the passengers from inhaling all the chemicals. So do you have any recommendations for what airlines should be doing during this process? Should they be keeping the airflow system on, are these chemicals safe to inhale? And what are the risks if the air flow system has to be turned off for some amount of time, for whatever reason?

LEONARD MARCUS: Jack Spengler, have you looked at that?

JACK SPENGLER: So I believe if they’re still at the gate and the machine comes around and de-ices, they could be hooked up to the preconditioned air system that is installed at each gate. And that’s providing air independent. And so the spray would not get into that air system. So they would easily keep the ventilation system up. I would be amazed, not to say this couldn’t happen, that they’d actually turn off the air system. You can’t have a plane full of people, closed box. Your CO2 levels would get very high and it probably would smell too good. So if that doesn’t happen, to the best of my knowledge, they might operate the APU, the auxiliary power unit, but they can operate that on a re-circ mode. So you’re still getting clean air for that short period of time because it’s going through the filters. But to be honest with you, you know, I’m going to look into this. This is a condition that I think will follow up on. Thank you for pointing it out. And we’ve all been on the tarmac, 21st in line waiting to take off. So we know that those periods of time can be extended. And that’s why we put such an emphasis on the adequacy of ventilation while you’re on the ground. So this is a condition I think we’ll look into further. Thank you.

Q: Thanks.

MODERATOR: OK. All right. It looks like that’s our last question. Dr. Marcus, do you have any final thoughts for us?

LEONARD MARCUS: Just want to thank all of you for us here at the university, we call this translational research. It’s important that the flying public and the public in general understand how they can make decisions about flying in every activity. And I think one of the messages that we want to send out once again, the importance of wearing masks, whether you’re on an airplane or wherever you might go in public, certainly supported by the research we’ve been doing here.

This concludes the October 28th press conference.

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