Coronavirus (COVID-19): Press Conference with Bill Hanage, 04/22/20

You’re listening to a press conference from the Harvard T.H. Chan School of Public Health with Bill Hanage, associate professor of epidemiology. This call was recorded at 11:30 am Eastern Time on Wednesday, April 22.

Previous press conferences are linked at the bottom of this transcript.


BILL HANAGE: Good morning to everybody, especially good morning to those who I haven’t had the opportunity to talk to you before. So, as we’re talking, we are – and these comments are going to be focusing upon the United States, although obviously, this is a pandemic and similar sort of things are taking place in different sort of stages all around the world.

As we are speaking now, there’ll be more than 40,000 recorded deaths from the pandemic in the United States. Those are concentrated in the northeast, with more than 14,000 in New York State alone.  I want to point out that that 40,000 is comparable to the amount that we would expect for an entire flu season over the country. And that’s just at the start of the pandemic.

Now there are also probably underestimates on the amount of disease in various places. And this is because testing remains inadequate. If you look at the number of tests coming back positive, they are in many places north of 20 or 30%, which suggests there being concentrates on those people who are needing to be tested because they’re in healthcare. Uncertainties do remain around the numbers of mild cases. And this is highly relevant to some early serological studies, both from here and around the world.

I would like to emphasize the importance of protecting the vulnerable. That includes the elderly and people who are in long term care facilities. And I think there are understandable anxieties and obviously there are understandable different approaches to what people characterize the lockdown. And I think that we need to accept that we are in the early stages of a pandemic, and as we’re moving forward, we should refine and improve what we’re doing in order to make it better and more effective. And I would like to emphasize that the pandemic is only just getting started. And I will now take questions.

MODERATOR: Thank you, Dr. Hanage. First question.

Q: Hi, thanks very much for doing this and taking the time. So, I wanted to ask about serosurveys. And basically, as you know, as these started to come out – instead of asking about a particular study or something like that, I wanted to ask how people, whether it’s journalists or public, whatever, should go about assessing them and what they’re reporting. What should people look for and what can they take away from these sort of local serosurveys?

BILL HANAGE: That’s a great question. And I think the first thing that people should look at is whether or not it’s a preprint or a peer reviewed study which has been published in a decent journal. That much is probably obvious, especially to people like you working for STAT.

The other thing is to think about whether or not it’s a truly random sample, or whether or not it is self-selecting. Some of the early ones have been – they’ve recruited people to take part in them through social media. And that’s not a good thing because it biases your sample very much towards people who want to be tested, who might suspect that they have had it. And that can lead you to overestimate the numbers of people have actually been exposed

You also want to be sure about negative controls – that is that the specific study in question that specific method, the test, is capable of distinguishing between the pandemic coronavirus and other circulating betacoronaviruses, because getting those confused obviously can have pretty dire consequences.

And finally, it is important, I think it is most important, to look at serosurveys which has been done where there has been a substantial first initial search, such as Lombardy, or perhaps New York, or there’s one coming out of Geneva in fact, which I’ve just noticed this morning. And these are particularly useful because of the fact that they give a greater opportunity to determine the real spectrum of severity of disease, because that has been enough of it that if you do a random cross-sectional survey, you’re going to be able to pick up enough people in each in order to be able to figure out what’s there.

Q: And yeah, just to follow up on that. I mean, I guess, like what are the specific issues that arise when you either have a small number of people, a small survey – a small sample, I should say – or if you’re surveilling in an area that hasn’t been hit particularly hard, kind of following up with what you were just saying.

BILL HANAGE: So yeah, so small survey. This hits things in both way. So, it’s a small survey can be inadequate to accurately assess the true proportions underneath. And similarly, if you’re doing it in an area which has not been very hard hit, you will have to take a very large sample to be able to accurately estimate the numbers of people in each category.

And you know, I don’t, I cannot speak to the motivations which underlie various things which have been published, or non-published, or other various things which have been put into preprints. But it’s possible that if you’re looking at a place which has not been hard hit, it’s really, really important to get a large enough sample which is random that you’re capable of accurately estimating the underlying truth. And you cannot cut corners by trying to use means of enriching your sample for people who have had the virus, because that, as I’m sure you can understand, will lead to very faulty conclusions. So, summarize: careful of preprints. Before you start working with anything which is in a preprint call up somebody like this and got someone like me and get my comments on it.

Q: Thanks very much.

MODERATOR: Next question.

Q: Hi, how are you? I have a few questions. I don’t know how much time I can take, but you know, to get back to your introductory comments. You mentioned that we were at the beginning of this pandemic. I’m calling from Canada, but there, you know, we are very much in the same boat with the US. At the same time, I’m watching very much – I have a blog on this and I am very much connected worldwide on the topic. And, Professor Raoult in France just announced yesterday that for him, at least in Marseilles, the pandemic was basically receding. And he has very concrete numbers on that. For example, there is ample testing in Marseilles and the people show up when they have the symptoms, they show up and they know, everybody knows in Marseilles that if you are sick, you can get testing and you can get treatment because unlike in the US, and certainly, unlike in the UK, unlike in Canada, there is  treatment pre-, you know, kind of early treatment that is provided in Marseilles. And they saw a sharp decline. That’s what he said in the number of people showing up for testing.

So, I’m just wondering what is your take on this. You see, why would it be receding dramatically in Marseilles? And basically, he sees a progressive return to some form of normal life, you see. Maybe not direct and with some form of social distancing and continuing testing and treatment. How’d you come to contrast the Marseilles situation with what you just described as just the beginning of a situation in North America?

BILL HANAGE: Okay, thank you very much for the question. The first thing is that I cannot speak for what’s in Dr. Raoult’s mind. What I will say is that it would be truly remarkable if you found a particular location, such as Marseilles, and of course I don’t know exactly what’s going on in the ground of Marseilles, I don’t think you would be able to – if you find a place that appears to be being very different from other places, then that demands explanation. You know, extraordinary claims do demand extraordinary evidence.

It is possible that as a result of the social distancing which has been taking place in Marseilles, or indeed other places, that the initial surge – and I’m using those words very carefully – has seen a peak and it’s then declining, but it’s important to note that that decline is not, we believe,  a result of immunity to the virus, but rather as a consequence of the actions that we humans have been taking in order to try and stop new transmission chains from being initiated.

So, it’s quite possible that cases are dropping – I mean, it is a point where you might expect them to be doing so – but, I think that is stretching credulity to suggest that that means that the pandemic is passed. In order for this pandemic to be over and the much-vaulted herd immunity to have been obtained then, depending on exactly your estimates on how transmissible the virus is, you would need somewhere between 60 to 75% of the world’s population to have been infected. And we don’t have evidence to think that that is what happened during the initial surge.

MODERATOR: Okay, we have a lot of questions, so I’m going to move on to the next one.

Q: Hi, everyone. So, in terms of reopening the economy, Trump’s three phase guidelines just recommended the dating criteria to loosen the restrictions. But what is the trigger of restricting again after reopening. I think we should come to a consensus on this issue, because it’s very important.

BILL HANAGE: Yes. See, I really appreciate that question. So, what I’m going to talk about – I’m just going to say a little bit now about the importance of opening the economy, but I’m really appreciate the way you framed it because of the fact that a prerequisite for moving forward needs to be the ability to detect if we have a surge building that is going to threaten health care. Now that means testing. And the other thing that is important is, exactly as you said, we should come up with agreed – certainly locally agreed but ideally at a larger scale on that sort of preconditions for taking different action in order to stem the threat of a future surge.

Now, I appreciate elements of the White House plan. In particular, I like the staged model and the way that it’s accepting that we want to be seeing a decline before we start reopening things. However, my concern is that there is not sufficient testing capability at the moment, in order to be able to determine whether or not you are seeing the risk of a future surge which is going to threaten health care again. And without that you are very much risking – you’re just sort of taking your foot off the brake at a very dangerous time.

And so, I thoroughly agree with you that that we should be coming up with an agreed predetermined trigger for taking off the reinstating action and what that might be. However, I can advise on what I think that might be to politicians but it wouldn’t be up to them to make the decision.

Q: Thank you.

MODERATOR: Next question.

Q: Hi, thanks so much for taking the call. The other day you were talking about the role that children may be playing in the infections. I understand that they don’t get that sick themselves in general. But could you talk a little bit more about their role in the transmission of this disease and what we understand?

BILL HANAGE: Certainly, certainly. It’s a really good question, at least for people like me who’ve got kids downstairs. And, you know, my spouse, my wife, is also an infectious disease epidemiologist and she’s on a Zoom call in the other room, and my children are – I bought them bows and arrows and I’m hoping that they’re not shooting anything inappropriate. So, the question is hugely relevant to school closures.

Children, we know, do not get sick at the same sort of rate as all the adults. The reasons for this we don’t know. But we know that they don’t get sick to the same degree. I think we are beginning to get some emerging evidence that young children may not play a great role in transmission, but I would not want – this is just very emerging. It’s extremely premature don’t want to be pushing this as a major defined message here. But there are some suggestions that, you know, adolescents might be a more relevant participant.

The problem is, unless we are able to thoroughly define the role of these age groups in transmission, it’s very, very difficult to predict the likely consequences of reopening schools or anything like that, because what we also need to be cognizant of is that children make contacts with each other in a different way to adults. So, even if they were less infectious per contact, they’re more likely to make more contacts per day. And as a result, the impact of reopening schools could be, you know, quite disproportionate. So, at the moment, we are still awaiting good data on the extent to which children can become infected.

And again, this comes back to some of the comments that I was making previously about serological surveys and antibody tests to determine who has been infected. Once again if we do those on children and we discover the children have been infected, that will be informative. However, unfortunately, it’s still wouldn’t tell us anything about necessarily how much they are contributing to transmission So, these are currently open questions and data are collected and as soon as we have something which is a little bit more secure, I’d be happy to speak much more precisely about them.

Q:  Thanks very much for answering that.

BILL HANAGE: Thank you.
MODERATOR: Next question.

Q: Hi, thank you guys. So, we’re working on a story today here about the metrics that leaders should be looking at as we struggle to responsibly open up the economy, such as like positive return rates on tests, hospital bed availability, you know. And this is, of course, in the absence of larger testing. We wanted to get input from experts on what data points they would be looking at if they were faced with this particular decision.

BILL HANAGE: So that’s a great question, and the first thing is can we please get more testing. I mean, I know that we’ve been doing this a lot, but I would urge people to be looking for more testing. I mean that’s like the first line of every article. The thing which I personally look at is hospitalization rates. And I try to take into account the criteria for people who are being hospitalized because sometimes people who are in long term care facilities are not necessarily counted within those numbers. What you want to see is evidence of a slowing in this, which would be indicative of a slowing in the community, a few weeks beforehand, in terms of community transmission. So, what I would ideally like to see would be confirmed cases in the presence of adequate testing dropping for two to four weeks.

However, we realize that that is not something which is likely to happen. So, in the absence of that other than saying that we have to be, you know – it’s more important to stem the initial surge. That’s a really important thing. I can’t emphasize that enough. If you’re looking for something else, then I personally look at hospitalization data, but it’s an extremely imperfect metric

MODERATOR: Okay, next question.

Q: Can you tell us how we should be looking at states or other smaller governments that may have had less strict orders to isolate, and how should we look at their rates of positives and deaths where they’re increasing but they’re still low? When do we say it’s about to take off? And how do we tie that to the government restrictions that may or may not have been place?

BILL HANAGE: That enables me to make a comment about something which is wider, so thank you very much. As it cannot have escaped your notice that there are a wide range of things which are being done in different parts of the United States. You know, for instance, if you look at California, there are many places where the schools are closed by local authorities, but there are others where they have not in some perhaps more rural regions.

Now how do we interpret the rate of take off in these places is really, really difficult in the absence of adequate testing, exactly what you’re saying. So, I’m afraid I cannot give you any definitive answer to that because it will very, very much depend on exactly what you’re looking at. What I will comment on is the expected behavior of an early pandemic. And remember this is still an early pandemic. We expect in smaller communities to see a reasonable amount of what we would call stochastic or random variation in the rates with which they take off. And the reason for that is because of the random nature of how many introductions erupt in the community and then how long it takes for them to get to get a foothold. If there is strong amount of social distancing going on, then it might take a while. But if not, and in particular if there are large gatherings of people, perhaps, as in some states, church services or other worship, then the opportunity could be for a relatively large number of cases to be kicked off fairly quickly and then those will be noticed.

It also depends – and this speaks to the piece of your question which has to do with testing – just how hard you’re looking, because it will take a – we expect it to take a little while for the most severe cases anywhere to become immediately apparent. And so, the first sign you might get is that, you know, your local emergency room is having way more people with flu-like illness and you would expect – and by the time it’s got to that stage, it’s probably too late to do very much about it. So, I’m sorry I can’t be more specific, but I hope that those general comments are helpful.

Q: Thank you. Okay.

MODERATOR: All right next question.

Q: Thank you so much for having us and taking my question. I just was sort of hoping you could help me think about testing capacity a little bit more can you can hear me. So, the WHO seems to recommend that you’ve hit a good testing capacity if you can get 10% or less positives. Can you talk about, sort of, is that throughout an entire outbreak? You know, if you’re at a peak, do you want to see 10% or less? And how does screening or testing restrictions play into that in terms of who gets tested? If you have symptoms, you know, random sampling I’m mostly talking about diagnostic testing.

BILL HANAGE: Those are good questions. So, the WHO number, it’s somewhat arbitrary in the sense that it varies. I mean, it’s the interesting thing about that number is, as you say there are different stages of the pandemic. There’s a point at which we’re trying to establish the actual total number of people who are infected at the moment. And then there’s the other question of how many are there in the community now as it’s ramping up, how many are left. So, it’s really quite different things depending on where you are that the stage of the outbreak.

So, at the moment we have a situation in most places – by the way, by saying it’s arbitrary I don’t want to say that it’s wrong. I mean, the fact is that it’s obviously a target, which is a good thing to be going for, and it’s very noticeable that most places in the United States are falling very far short of it. At the moment when you have limited tests, it’s really important that you use them on the people to ensure appropriate treatment for the people who are in healthcare.

And the difficulty with that is that it completely hinders our ability to determine the actual spectrum of the severity of infections.

So, it’s right. In fact, I have a whole op-ed which I wrote, which is founded on the rocks of editorial something or other somewhere. It’s right if you have limited tests that you should be applying them to people who need them in healthcare, and then to health care workers. And then perhaps as you start getting more, you can start doing good contact tracing out in the community, although if you’re doing that at this stage, then you’re going to rapidly be finding that your numbers of contacts, unless there’s social distancing going on, are going to be increasing exponentially, so it’s going to be a really tough thing to do.

So essentially, we do need more testing. In the absence of sufficient testing to be doing it widely in the community, we need to be focusing on the sickest people in healthcare. We also then need to be focusing upon the health care workers and noticeably – this is very serious – people working in long term care facilities and the patients there, because if you can identify an outbreak and a long-term care facility earlier, then you’re going to be able to handle it better and limit the resulting disease. And then after that, if you have tests left over, then you should be going out into the community and trying to do something to estimate community prevalence. So those are sort of the order of things which you should be using them. Of course, the fact is we don’t have enough. You know, these are these are sort of testing times in more than one sense of the word.

Q: Thank you.

MODERATOR: I’m going to break in real quick. We had a question is going to follow up on that, I think, pretty well. We’ve heard conflicting estimates about how many tests we quote need to grasp on the extent of infections, with the US performing 150,000 tests a day, but administration officials saying that we need about one and a half times that, so about 6 to 7 million a month. Is that realistic and how many tests do we need?

BILL HANAGE: The unfortunate answer to that is that I don’t like the idea of putting a single number on to things, because if you put a single number on to things, you basically end up creating it sort of target for people to go for. And if you start hitting a target, then people never ask if the target is the right one.

It’s true that we essentially need more testing, both virologic, both protecting people who are infected and determining those people who have been infected. The reason this is crucial is that we are still struggling to understand precisely how many people are infected with milder symptoms and the only way that we will be able to tell when we are doing enough of them is when we have done enough tests in the community and we’re beginning to find that the numbers of people coming back are dropping. At the moment, the different trajectories in different parts of the United States are almost certainly tracking the ability to test rather than the actual numbers of underlying cases. So, this is a really important. In order to answer it definitively, I would need to have data from a huge study which has not yet been done.

MODERATOR: Next question. Please go ahead.

Q: I just wanted to know, as states look to reopen, how should they detect and root out asymptomatic people? It seems like finding a needle in a haystack without the ubiquitous testing. Are there certain strategies that might pay off, like targeting vulnerable populations and crowded cities nursing homes? What should they be doing to be more targeted about this and find those folks?

BILL HANAGE: So yeah, that’s an excellent question. The first thing to say is that obviously looking for people who are vulnerable individuals is really important and that means like, you know, health care facilities, nursing homes, perhaps assembly line conditions, things like that. I would also suggest that there could be – and there are various suggestions at the moment of various different possible approaches to contact tracing which could be employed.

So, as you’re reopening, what you can do is, you can obviously aggressively try and find every contact of every known case and start asking whether or not they are asymptomatic. And indeed, if you do that you do find a substantial fraction of individuals who have minimal symptoms.

And I mean exactly how many of them there are is unclear, because you know these, you’re biasing towards people who, you know, haven’t been exposed to a known case.

Building out from that, I think that the important thing to understand about asymptomatics at present is that we, we know that there are a lot of them, we don’t know how many. In terms of contact tracing there may be some things that we could do, which will be a little bit cleverer.

I know that there are multiple people who are working on developing digital means to assist in contact tracing. There are a lot of apps which are, for instance, tracking foot traffic or other mobility data and it is quite feasible to develop something which would enable an individual who had the app to be able to tell if they had been potentially exposed. And then if you had testing capacity, you’d be able to direct tests to those people and if it was rapid enough, they would be able to figure out whether or not they actually were positive and currently asymptomatic themselves. So, and these are, I should point out these things are not existing anywhere in the United States, at the moment, but they are something which could be a part of the solution.

I would also want to make a brief comment that whenever you hear people talking about asymptomatic, it’s important to distinguish between asymptomatic now and asymptomatic throughout infection because they’re not necessarily the same thing.

MODERATOR: Okay, next question.

Q: Hi. How are you, thank you for doing this, by the way. One of the first things a lot of states are looking at doing as they reopen are loosening the restrictions on elective surgeries. CMS has put out some guidelines that are relatively vague or give a lot of flexibility to the states, talking about having a sufficient amount of bed capacity or an adequate number of PPEs. I’m curious if you have any thoughts as we see states sort of doing this, creating their own guidelines, you know, or Louisiana, for example, said five days of PPE on-hand is enough and is looking to go. What do you think about when States should start allowing people back into hospitals for elective surgeries?

BILL HANAGE: So that’s an excellent question. I think that the difficult thing about elective surgeries is, among other things, the risk to healthcare because we’ve been talking a lot about asymptomatic people and people who have been coming in for elective surgeries could be asymptomatic as well. I mean, we can test them before they come in. But, I mean, that is sort of an absolute necessity. We’ve also been talking about how short testing has been.

And I think that I would ideally like to see that local hospitals and ICUs had a large, kind of, real capacity to handle many times the current number of COVID patients at each level of severity. So, and that’s, I should point out, a moving target because as we are treating this we are learning things about it.

You’ve probably noticed that ventilator demand, though high, has not been as high as some predictions and that’s partially because of the fact that we are learning to treat patients in ways which avoid requirement for a ventilator, which is a good thing because nobody should want to be ventilated if it can be avoided.

I would be, myself, extremely cautious about allowing elective surgeries in the absence of adequate testing and of course there must be absolutely adequate PPE for all people throughout medicine. The strain on the supply of personal protective equipment has been extremely acute and even though we are, you know, even though many places have adequate supplies there are also many places that don’t. And as I said, starting out, if you get a new surge building and you don’t detect it then you could be in a very bad situation comparatively quickly. I would hope that anywhere around the country looks at how quickly this introduced itself to New York and makes their plans for the future accordingly.

MODERATOR: Okay, next question.

Q: I am very interested in studying mortality rates and success rates on different treatment protocols. I want to address an issue with these randomized trials because when they involve placebos and you’ve got somebody who’s got a very dangerous disease with a high fatality rate, it feels unethical to me to be treating them with a placebo and condemning them to a higher mortality and equally I’m very uncomfortable with the idea of randomized, selecting patients to one or one or another arm on a random basis, instead of allowing the doctor the discretion to select what he believes is going to be, have the most likely success rate for his patient.

I’m much more in favor of approaches where clinicians, such as in my say we do pre-, pre-publish. And yes, it’s a growing science and a growing evidence and we all realize that, but they are pre-publishing evidence of the success rates that they are observing and enabling conditions to make, you know, decisions based on the experience of others. And when you see case fatality rates of 10 in 1000, yes, I haven’t seen the distribution of age amongst those 10 or the thousand, it is still a much lower case fatality rate than we’re seeing in, for example, the United Kingdom, where that treatment has not been approved, even approved for COVID-19 cases. And I’m also very troubled by some of he some of the trials where the dosage that’s being applied in the trial is, in some cases, triple the dose that’s being recommended by those that are having success with that treatment, I say triple in the early initial dosing stage and, you know, I’ve just, there is no question, they were a set of comments. So, the question is, you know, what is your answer to these challenges because I detected from the start of the presentation, and thank you for making yourself to present, that you were very much in favor of traditional randomized statistical surveys

BILL HANAGE: So, I should say that the initial thing that I was talking about was about serosurveys rather than treatments. There are considerable ethical challenges around designing randomized control trials in a situation like this, and I won’t speak to them specifically. What I will point out, though, is the importance of appropriate inclusion criteria and that means that you’re comparing the same kinds of people across different things. You can find, for instance, in some cases, and I’m thinking of a particularly recent early study of some of these experimental treatments which came out from Marseille, or from Didier Raoult, which was actually suggesting a relatively high mortality rate among some treated patients. Now, the thing which is difficult to control for here is that we don’t know the underlying variation in terms of the, we don’t know the underlying sort of clinical spectrum, the severity of the disease and so on. And it could be that these are reserved for people who are particularly sick.

Without that it is very difficult to interpret. So what I’m going to point out here is that it’s extremely hard to interpret trials that have been done, especially trials which are short. And especially trials which have been poorly designed and I will also point out that some of the drugs that people are using in this can themselves have side effects.

And I hope that I can leave it at that and we can sort of have it. I believe that my colleague Marc Lipsitch has done a substantial amount of thinking about the ethics of trial design, and you could probably get on and talk to him in a day or two.

MODERATOR: Hey, next question.

Q: Thanks. Hi. Sorry to bother you, again. I wonder if you could talk a little bit about what we know about the infectious period of this disease. How, how infectious are we when we’re asymptomatic. Do we know anything about that and how that progresses as the disease progresses?

BILL HANAGE: That’s an extraordinarily good question. I’m going to preface this by saying that this is based on, sort of, some preliminary data that I have been working on. So please, treat it as a pre-print and get further content from other people. It’s also based upon, if you look at work that was coming out of Hong Kong, I think it was last week, although to be honest, I can’t remember which week is which, and I can never remember which day of the week it is, indicating sort of studies of a range of patients, including checking out viral loads and viral shedding from different parts of the respiratory tract.

Taken together, I think these things point to a substantial infectiousness during the asymptomatic period. We have known for some time, or at least I have known since February, because I was fortunate or unfortunate enough to be able to talk to people about some early patients, that you can have people who have abnormal chest CT but are otherwise ,well they are asymptomatic. They may spike a fever or they may not have anything but if they’ve got an abnormal chest CT that is indicating pathological process and we are now beginning to be able to tie that to the capacity for asymptomatic transmission.

The other thing is that there is data also emerging that if you compare people who are asymptomatic with people who are symptomatic, the viral load that is being shed from them is pretty similar. So once again, that suggests that there is a substantial amount of pre-symptomatic or asymptomatic transmission. And I think as I said from work that I’ve been involved with myself, but this is so early stages, it’s not even quite as a pre-printed out so I beg you to treat it as informed comment, rather than gospel truth that if you look at the sort of serial interval, the time between cases in sort of early well studied transmission chains, it certainly points to a burden of infectivity which is really quite early on. So, in other words, I’m restating the importance of the pre-symptomatic or asymptomatic stage of infection and that of course is absolutely crucial to the fact that this is a pandemic.

MODERATOR: Okay, next question.

Q: I kind of had a follow up to that question in terms of pre-symptomatic transmission You know, what’s your current thinking in terms of—I’ve heard some speculation and I have not looked at the data on it if there is any about, sort of, viral load. You know, if it’s like basically the initial dose might relate to disease.

BILL HANAGE: Yeah, yeah, yeah, yeah.

Q: So what’s your thinking on that in sort of the role of potential pre-symptomatic transmission.

BILL HANAGE: Yes, I think that that’s a very. That’s a very interesting question. So, first of all, I’m not entirely sure of very great data out there, but that might be my ignorance talking. One of the things which is quite interesting is that the impact of the, I think you have to think about also possible differences between the exact route of transmission or how somebody becomes infected.

Because you might think, for instance, we had a conversation in the call last week or a couple weeks ago about some people who are in fact while singing in a choir. And the point is that, if you’re infected while singing you’re both shedding virus, but the people who you’re infecting are breathing in very deeply and it’s getting very deep into the lungs. So, could be not only a dosage effect, but also something to do with the amount of gets into a particularly vulnerable part of your body.

I think that the science is evolving on that. I think it’s a great question to ask, and I wish I was able to answer it more thoroughly.

Q: Thank you so much

MODERATOR: Next question?

Q: Yeah. I also wanted to follow-up on the question that I had asked if you don’t mind. Going on, which was about elective surgeries and just sort of probe a little bit on what you said before about having an adequate supply. I know you don’t want to put a number on it but are there ratios are metrics or anything that you would suggest as guidance for hospitals to be looking at, either based on their own capacity or their community. And then the second part of that is, should this in your opinion, should this be a local, county by county or state by state decision. So where we may end up seeing somebody with, I’m making this up obviously, but the ability to get a colonoscopy in Arkansas that you wouldn’t be able to get in Oklahoma, even though the spread of the virus is the same or close to the same in those two communities.

BILL HANAGE: Yeah, so I mean that’s actually a really smart question. So the first thing I’ll say is that in conversations and sort of, the kind of things that we have been saying at the Chan school among ourselves about I’m criteria for relaxing a lockdown, the number that we think about is enough to handle 10 times the current number of cases you have now, but that is in that is a general number for relaxing the lockdown for getting a step out of it. And that is not necessarily what you’re proposing because I mean just doing elective surgeries or elective procedures is perhaps a milder form of that. And also, I want to point out has the potential to be life-saving in and of itself, you know. Getting a colonoscopy, when you need it can be a life-saving procedure if it detects colon cancer early enough.

You point to a difficulty there which is which I’m not really in a position to be able to talk about in depth, but I’m going to raise it anyway because I think it’s something that should be part of the discussion, which is that we want to be careful that we do not end up in a situation where there are, it is very different, in your ability to get some access to some parts of health care in some places than others because if you could get that kind of health tourism going on, then you might run the risk of fomenting transmission in a local area as a result of what was going on next door.

I mean, the problem is, and I’m going to, I’m going to quote. I mean, the difficulty is that because this is a pandemic that as people, as we move out of lockdown, that as people move around, then you run the risk of reintroducing it to other places. This is what’s been happening, you know, you’ve seen this in China. You’ve seen this in places which are otherwise been doing pretty good control. Movement around in the healthcare system could be a way of

making it worse and the healthcare system, in particular, the non-COVID cohort, is one that we should really be wanting to protect, partially because of the fact we know how bad COVID is for patients with comorbidities. And so, you really shouldn’t be doing everything we can to protect them.

Sorry, I can’t be more precise about that, but some of these things are more political than an epidemiologist can handle. We can give you the best of the advice though.

MODERATOR: Hey, next question.

Q: I read the students and families are making housing deposits for dormitories in the fall. Can you compare and contrast? We’ve seen outbreaks in congregate housing and prisons. I’ve read about asymptomatic outbreaks in farmworker housing. How do those settings compare and contrast with the risks that might be present in a college dormitory setting, if we’re talking about the spread of COVID?

BILL HANAGE: Yeah, I think I missed the first part of the question, but I think I’ve got enough. I mean, we know quite a bit about sort of risk factors for transmission and one of them includes like core ventilation and another includes making a large number of contacts. So any setting, which is like, either, a prison or in detention center or indeed congregate housing has a real risk of adding to transmission and getting a large number of infected individuals.

Now while people who are in college dorms are unlikely to be of the age group which is most severely affected, we need to remember that firstly, that age group can get infected and can be really severely ill. I know of at least one person in their 30s who sent my wife a text saying, “this is the worst I’ve ever had. I wish I could go back and warn people.”

Not that that have listened, which is unfortunately true. We know that they can get really sick.

But more importantly, we know that even if they don’t, they can then transmitted to others and you really want to limit the pace with which the infection is building in the community, because as I’ve said a few times but it’s worth saying again, we are still in the early stages of the pandemic and we are seeing an initial surge and that initial surge is being brought under control in some places. In other places it’s only getting started.

And we will be with us for probably quite some, well, it will be with us for some time. And so, these problems, these questions are going to be acute in the fall, and you’re going to be wanting to take very careful decisions about them to avoid the potential for future surges and with their impact on healthcare.

MODERATOR: Next question.

Q: Yeah, thank you. Um, it seems like this disease is somewhat of a Russian roulette for people in that some really get knocked out by it and some don’t have many symptoms or mild symptoms. I’m talking about relatively healthy people not older people, or those with chronic conditions. What explains that, we talked about the dose, but are there other factors such as genetics, your immune response. Um, what else is there.

BILL HANAGE: Yeah, it’s a great question and it’s one which I can only respond to in generalities because it’s still an area of active research. And it’s also the kind of research, which I am less involved in. It’s more kind of sort of question of virology or pathology. But I can speak generally about it.

There are, there may be a genetic component, which means that it’s possible that some individuals may be more vulnerable for reasons which we currently do not understand possibly variation in the receptor which the virus attaches to which is the ACE2. And it’s possible that that explains some of the interactions with people who are on particularly, who are having some certain co-morbidities.
It’s also probable that there are differences in the immune response as you go through age and depending on the number of times you’ve been exposed to other coronaviruses. Which might have something to do with why older people get so much more sick, but there could also be a thing about if that were the case—and I’m saying if, because this is in that category of questions, which I’m not saying because I know, I’m saying because of the fact that it’s a plausible thing—that, if that were the case, and again, younger people, some of them would have had more coronavirus exposure in the past than now. So that also could be a part of the piece.

But, you know, these are a few examples. And I think the bigger message I would put across is that it’s a tremendously complicated problem that we’re only starting to learn reasonable answers to.

MODERATOR: Okay, next question?

Q: Hey, listen, so you see the course, we’re on in terms of the lifting of restrictions. You understand the course of testing, which seems to be what gears, the outcome. And you obviously have an expertise in this space. So, what’s your forecast on what happens here. Like, do we see a doom scenario where we all relax and take it easy during the summer and then it comes roaring back in the fall, and we have to do a complete lockdown again? Is that likely or some different course or just what’s generally your forecast and what happens from here.

BILL HANAGE: And that’s, I like the easy questions.

Q: So, you can’t say you don’t know, that’s where you’re going.

BILL HANAGE: Well, I’m going to say I don’t know, but I’m going to tell you some things anyway because which are important. The first is that if we relax everything in the summer, I don’t think we’d be waiting until the fall. The important thing, the reason why flu goes away in the summer is that there’s a lot of seasonal forcing, which means that it transmits less well in humid conditions, warm, humid conditions. It likes cold dry conditions.

Now, we don’t know for sure what the amount of seasonal forcing is with this, but if we go by what we know about other coronaviruses is it’s not as strong. So, and you can see that in, for instance, I mean, I think, Singapore, just announced, go check this because this is from memory. I think Singapore just announced jumping, you know, in terms of hundreds of, possibly even thousands of cases there and that illustrates that it can transmit, if it can transmit in Singapore, then it’s not going to be being held back in other places.

However, I do think we, I think it’s possible that we might catch a break and it would be less transmissible during the summer. Whether or not it is we’re going to have to see, we’re going to have to look carefully. But the, what we have to remember is that as we start changing things, the opportunity for future surges could be there. And that’s why my advice to folks right now is essentially to recognize we don’t have sufficient population immunity to be able to, we just don’t have enough population immunity that we need to see at the moment, to be able to start relaxing our guard.

We should be ready to be doing other things. And this is what I said at the beginning, we should be trying to think of ways to refine what we’re doing now. That’s the way that they’re describing it—I heard this from the European CDC—but they’re talking about refining lockdowns because by refining them you’re trying to focus in on the things which are most helpful and which are most sustainable and which are going to have the largest effect. And we will probably learn more about what those things are by looking at what happens in different parts of the country to the disease trajectory as different steps are taken. And that means that we are going to be trying to design this as we go along.

I really think it’s extremely important that we manage to balance our response to this with economic activity. But I think that one of the things we’ve got to remember is that we should keep a very close eye on it. So in response to your comment about the second wave, second waves of flu things, and this isn’t flu, but future surges, they definitely could happen, but I don’t think we’d be waiting until the fall. I think we’d see evidence of that happening before then.

Of course, if there is seasonal forcing and you see a little bit of stuff going on over summer, then as we move into the fall we would see it ramping up again and then we will have the really unpleasant situation because right now if you see somebody, you know, with a fever and a cough, or indeed without because there’s a lot of asymptomatics, right now if you see someone with viral respiratory symptoms, there’s a good chance that they’ve got COVID. Whereas if you take that to October and November, you’re going to be having to distinguish between that and flu and that is not is going to be a whole other question, which is probably going to be better answered then than now.

Q: So do you think we’re back to a full lockdown then at some point. I mean, why wouldn’t we be if there isn’t really a way to stop the spread?

BILL HANAGE: We might be if we don’t accept that we’re going to have to take, I mean, I think this is one of the crucial things. I don’t think you need to have full lockdown. I think you need full lockdown in response to surges, which are threatening healthcare. However, there are milder things we will not be able to do

Q: Great, thank you.

MODERATOR: Okay, it looks like we are out of time for today. I just wanted to say thank you for to Dr. Hanage. Did you have any final comments you’d like to make?

BILL HANAGE: I think my final comments and probably based around roughly those, which I have been making for others, which is thank you all for coming in. Thank you all for the work you’re doing. And I am very, I think one of my major concerns at the moment is I’m detecting a sense among folks that this is coming to an end. Whereas actually, we’re really just in the beginning. If we accept that, if we accept it’s bad, then we can start really valuing all the things that are going on to make it better.

This concludes the April 22 press conference.

Richard Serino, distinguished visiting fellow at Harvard’s National Preparedness Leadership Initiative, former Federal Emergency Management Agency administrator, and former Chief of Boston EMS (April 20, 2020)

Michael Mina, assistant professor of epidemiology (April 17, 2020)

Barry Bloom, professor of immunology and infectious diseases and former dean of the school, and Bill Hanage, associate professor of epidemiology (April 16, 2020)