Epidemiologists answer lingering questions about the virus


Watch the AMA's daily COVID-19 update, with insights from AMA leaders and experts about the pandemic.



In part one of a two-part series, AMA Chief Experience Officer Todd Unger talks to three epidemiologists who help answer lingering questions about COVID-19, including if the virus has been more difficult to investigate than other diseases.

Learn more at the AMA COVID-19 resource center.


  • Ilse Levin, DO, MPH, internist and epidemiologist, Mid-Atlantic Permanente Medical Group
  • Harris Pastides, PhD, MPH, epidemiologist and president emeritus, USC
  • Preeti Malani, MD, chief health officer, professor of medicine, University of Michigan

AMA COVID-19 Daily Video Update

AMA’s video collection features experts and physician leaders discussing the latest on the pandemic.

Unger: Hello, this is the American Medical Association's COVID-19 update. This is part one of a two-part series with three epidemiologists who will help answer some of the many lingering questions about COVID-19.

I'm joined today by Dr. Ilse Levin, an AMA trustee, and a board certified internist and epidemiologist, as well as a hospital-based physician for the Mid-Atlantic Permanente Group in Silver Spring, Maryland. Dr. Harris Pastides an AMA trustee and president emeritus of the University of South Carolina in Charleston, South Carolina. Dr. Pastides has also worked with national and international organizations, including the World Health Organization, and the National Institutes of Health on matters involving higher education and public health. And Dr. Preeti Malanih, chief health officer and professor of medicine in the division of infectious diseases at the University of Michigan in Ann Arbor, Michigan. Dr. Malani is also an associate editor at JAMA. I'm Todd Unger, AMA's chief experience officer in Chicago.

As epidemiologists, your job is essentially that of a "disease detective." Has COVID-19 been more difficult to investigate than other diseases? And if so, why Dr. Levin, why don't you start?

Dr. Levin: Sure. I think one of the big difficulties has been being able to test patients, having testing that's rapid and that's easily available has really held us back. One of the other problems has been recognizing the patterns; knowing what you're seeing, and not limiting what the presenting symptoms were when you decide whether or not to test a patient.

Unger: Dr. Pastides?

Dr. Pastides: Yes. And I would certainly add it's a novel coronavirus, but the most important word is novel. And so, it is, of course, more difficult to get a handle on than things we're familiar with, but science is moving forward. We now understand the pathophysiology, and the clinical course of the disease better before. We just haven't had enough time to get our hands around it. But I'm very confident in another period of time, and in a year from now, we'll understand it much, much better. It is just a brand new disease.

Unger: Dr. Malani, because we are in the process of learning so much, there's still a lot to establish. Do you find that confuses people that the science doesn't change, but develops?

Dr. Malani: I do feel it's confusing, particularly, to the general public. And the best example is the data around masks. Initially it was, don't wear a mask. Now, it's always wear a mask. And there are other examples like that. So, the communication piece, and keeping everyone up-to-date is part of the difficulty.

Unger: Well, we typically use modeling to help track and predict the course of a disease. So, let's talk about that. Dr. Pastides, how has modeling been helpful with COVID-19? And how much can we rely on it? And what has it told us so far?

Dr. Pastides: Well, it's still a tad early. I think that's what the issue right now is. We've got data analytic capabilities like never before, but still, I mean, we're equipped to run through hundreds of thousands, if not millions of data points, we just don't have enough of them. And so, what you'll like to see is a stability, or a conformity through an iterative process. And we're just getting to that point now, but during the early part of the pandemic the data were very labile. So, week by week, we would see major changes in the predictability. So, there is no doubt that in a year from now those big data analytic tools, the convergence, the Bayesian probabilities will allow us to understand COVID-19 much better than we can now, but we're rounding the corner.

Unger: Dr. Levin so much about modeling, of course, is about the inputs. What are the trickiest inputs, or the things where the assumptions have been changing over the course of this pandemic?

Dr. Levin: So, knowing the patients who are positive for one thing versus hospitalization and death. When you're looking just at patients who test positive, well, that's less certain. You're going to have a limited number of patients who are getting tested, first of all, compared to the general population. And then, from that, we've seen a large problem with patients testing falsely negative. And so, that is a less certain entity than if you're looking at deaths and hospitalizations.

Unger: Well, one of the things I think people are always looking for is some kind of cause, what caused COVID-19? We've heard a little bit about this. Has any information, or new information emerged? And how does causation help inform prevention, including treatments and vaccines, Dr. Pastides?

Dr. Pastides: Well, let me start with the wet markets in Wu Han. And, to me, that's still the best guess. I would say, it's a very educated guess right now. And so, I'm alarmed that, at the global level, we still haven't had policies that attempt to ban them. Now, I know there are cultural issues. It's easy for an American to say ban them, not so easy if you're used to shopping there, and profiting from that. But I do believe the proximity of bodily fluids of animals, exotic animals, all together make the jumping of viruses from whether it's a pig, and a monkey, and other things like that to the human, much more likely in the future. We've got to prevent that.

Unger: Dr. Malani, how does what we know inform treatments and prevention?

Dr. Malani: Yeah so, treatments and prevention are interesting concepts. And, I would say, one of the big changes clinically is initially we were very focused on the respiratory issues that this was a respiratory virus, of course, and we focused on pneumonia and respiratory failure. And, as we've moved along, we've learned that there's also a larger inflammatory component, and that there are residual issues that continue, and we're still learning. And the big one that we're hearing a lot about are cardiac issues, particular myocarditis in younger people. So, the idea of how we treat is changing, and we're focusing a little bit more on inflammation. And, of course, there's been some good data on dexamethasone. But understanding who benefits and then, ultimately, getting to a vaccine that's safe and immunogenic.

Unger: Another area that you look at is how a disease may adapt or change. And we've seen this with COVID-19 as it mutated since its initial onset into what effect, Dr. Levin?

Dr. Levin: Sure. So, the original strain that we saw D614, appears to have been less virulent. The new strain that we saw coming through Europe, and the US, and has now spread, G614, looks to be about 10 times more infectious. So, that certainly affects the spread of the disease as well. Now, as far as deaths go, and overall looking at how people are affected that doesn't appear to be as different, but the issue is the larger population that's infected.

Unger: So, much more communicable, but the jury is out still is what you're saying in terms of death rates?

Dr. Levin: Yeah.

Unger: Dr. Pastides?

Dr. Pastides: Yeah, mutations have been seen. I worry, therefore about vaccine development. So, we've got to get a vaccine that covers all of these, if you will, mutants. And so far, I think, the news is hopeful in that, as Dr. Levin said, there have been mutations, and variability with the transmission of the subtypes, but we want a vaccine that will encompass and protect us from all of these. And I think the news is hopeful. It appears that they're similar enough that they should be covered by a good vaccine.

Unger: Well, let's talk about what can we do, at this point, when the virus appears to be out of control in so many parts of our country. Is a nationwide lockdown the only way to control spread? Or what are the other options we should be looking at? Dr. Malani do you want to start?

Dr. Malani: Sure. I think we have come a long way since March and April, where really most of the country was under a stay-at-home order. And we have more testing, and we have learned a lot, particularly about mitigation and masks. And so, I am hopeful that we don't need to go back to, certainly, a national situation where everyone is sheltering in place. But there may be communities where we need to sort of scale back reopening. And as we're getting into the fall, and people are moving around more, and the weather's changing we're going to have to keep a very close eye on things, and actually be open to being very nimble and pivoting in terms of mitigation. But, to me, it's really the physical distancing, and the masks that are most important.

Unger: Dr. Levin?

Dr. Levin: I would absolutely agree with that. I think we've seen that masks work. We've seen that physical distancing works. And we have seen communities able to open up again. But we do have to be pliable, not just as the doctors, the epidemiologists, but also as the population, to the fact that there may be more outbreaks, even if they're in small pockets. And when that happens, pulling back a little bit, I don't think we have to go on a complete lockdown again.

Unger: Well, that concludes part one of our series. I want to thank Dr. Levin, Dr. Pastides, and Dr. Malani for being here today and sharing their perspectives with us. We hope you'll join us for part two of our update tomorrow. In the meantime, for updated resources on COVID-19 go to ama-assn.org/covid-19. Thanks for joining us, and please take care.

Disclaimer: The viewpoints expressed in this video are those of the participants and/or do not necessarily reflect the views and policies of the AMA.