Mark Lurie is an epidemiologist and expert in infectious disease at Brown University's School of Public Health. On this episode he talks with Sarah about the underlying issues of the coronavirus pandemic: how the virus spreads, what can be done to slow it down, and the different ways it's being treated by countries around the world. They also discuss lessons we can learn from previous public health crises in fighting this one, and how the pandemic is interacting with other social and economic issues.

You can learn more about Watson’s other podcasts here.

[MUSIC PLAYING] SARAH BALDWIN: From the Watson Institute at Brown University, this is Trending Globally. I'm Sarah Baldwin. On today's episode, I talk with Mark Lurie, who's an associate professor of epidemiology at Brown University School of Public Health and an expert on infectious diseases.

It's Wednesday, March 25. The virus has been found in 168 countries where it has sickened more than 412,000 people and killed more than 18,000. Prince Charles has the virus. India is on day two of a total lockdown. And in the US, Congress and the White House seem to have negotiated their way to a $2 trillion stimulus package. But by the time this episode goes live, things will undoubtedly have changed.

But for now, Mark, who's just back from South Africa, has generously agreed to bring us up to speed and bring us some clarity in what are confusing and unsettling times to say the least. Mark, welcome to Trending Globally.

MARK LURIE: Thanks for having me.

SARAH BALDWIN: Let's look at the general state of affairs of the epidemic in the US today. You've said that the worst is yet to come. Can you elaborate on what you mean?

MARK LURIE: Sure. The simple explanation is that the cases that we're seeing today are people who were infected up to two or three weeks ago. So there's a natural lag time between infection and when people if they're lucky enough to actually get tested or when cases are identified. So almost by definition, because we know that the epidemic continues to grow, there are many more cases out there that have not yet been identified.

Even with the cases that we know of, the data is alarming. We're currently in the US-- we've had 52,000 cases as of yesterday, March 25. And we're having about 10,000 new additional cases per day. I think it's fair and safe to say that New York is now officially the epicenter in the United States. There's a total of 26,000 cases in New York. And that's approximately half of all the cases nationally. And that is quite alarming.

If you look at the other three states with the most number of cases, those are New Jersey, California, and Washington state, New York actually has 10 times the number of cases of any of those states, seeing almost half of the new cases that we see each day in the United States. The population prevalence--

SARAH BALDWIN: And Mark, why--

MARK LURIE: Go ahead.

SARAH BALDWIN: I'm sorry. I was just going to ask why that is. Is that because of the population density?

MARK LURIE: For sure, population density has a huge role to play here. Obviously, as people are closer to each other, social distancing is much more difficult. So in a place with high population density, infected people are likely to come in contact with multiple uninfected people, giving them the opportunity then to infect them.

If you live in a very rural place where you have little contact with other people, then there is a kind of natural social distancing that already occurs such that urban epidemics are likely to be the places where most of the cases are seen.

SARAH BALDWIN: And New York City is currently on lockdown. Do you think that's going to have a positive effect on the spread?

MARK LURIE: I think if people follow closely the guidelines that are being recommended in New York and indeed federally and do so for long enough, I have little doubt that that will have a major impact. What you're able to do with social isolation is to block chains of new infection.

If people are not isolated, then we have many people with undetected infection who are walking around in the population who have the potential to infect other people and not even know that they're doing so because they don't have symptoms and have not themselves been diagnosed.

So this is a big problem that we're facing all over but particularly in urban areas where people are so tightly clustered. If you're able to break that chain of transmission, then you have an opportunity to really slow the spread of the virus.

Of course, this has to be done for a concerted period of time. Nobody is willing to say exactly how long that is. But given what I said before, we know that we're going to have a lag period of a couple of weeks. And so similarly, we would expect that the impact of these new measures wouldn't be seen for multiple weeks as well.

SARAH BALDWIN: So say by lifting lockdowns prematurely around Easter would probably not be a good idea.

MARK LURIE: Well, I think we have to wait and see what happens by Easter. But you'd have to be a real optimist to think that there would be sufficient scientific evidence to lift the restrictions by Easter.

For sure throughout the United States, the number of cases are going up. A small handful of countries have witnessed the peak of their curves and are now on the downside. Even Italy, which experienced, I believe, the largest epidemic in Europe, is starting to see a diminishing number of cases. In the United States, we're not at that point yet. We're seeing an increasing number of cases with each passing day.

It's also worth mentioning that we talk about cases. And we talk about 400,000 cases in the United States. What is very important to recognize is that those are cases that have been tested and positively identified.

However, they make up only probably a small proportion of the total number of cases that exist in the country. And that's because we've been slow to ramp up testing. And our rate of testing has been very low. In fact, many people who have potential symptoms who, let's say, aren't considered senior citizens or aren't considered at high risk for bad outcomes have actually been told specifically not to test because we don't have enough tests for everyone.

So for sure, the true number of cases is considerably higher than what we've already detected. And some scientists think that the number of true cases is probably 5 to 10 times the number of cases that we've actually detected.

SARAH BALDWIN: Oh, my god. So in the millions. possibly.

MARK LURIE: So probably in the millions. If you go with a high estimate, then that would be about 4 million people infected in the United States today--

SARAH BALDWIN: [INAUDIBLE].

MARK LURIE: --which is an incredibly high number. And I don't want to be alarmist. But smart-thinking people and scientists have estimated that's probably somewhere between 5 and 10 times the number of cases that we have actually identified through testing.

SARAH BALDWIN: But speaking of testing, is it even conceivable for testing to happen in the US on a scale, say, that was successfully done in South Korea?

MARK LURIE: Well, not at the rate that we're going. South Korea tested about 300,000 people. That's a per capita testing rate that's about 40 times higher than the testing rate that we've had in the United States. So we'd have to roll out tests in a very, very rapid way across the country in order to achieve rates that are even roughly similar to what South Korea has done.

And that's part of the reason why South Korea is one of the few countries that have been able to bend the curve. By conducting so many tests, they were able to identify a large proportion of the actual cases that exist, whereas in the United States, that proportion of cases that have not yet been identified is very, very high.

So when you're able to identify most of the cases, you then have an opportunity to isolate those people, to contact any of the people who they may have come in contact with, and to isolate those people. And that's a basic function of epidemiology to find who's tested, to isolate those people, and to find people who've been in contact with those people, and to isolate them.

SARAH BALDWIN: It's just hard to imagine that being done on that scale in the United States. But it sounds like we should be.

MARK LURIE: Yeah, at this point, it's impossible to imagine that because the rate of testing that we've achieved so far has been so low. It took us a long time to react to the epidemic. It took a mistake by federal authorities which sent out tests that were not entirely accurate and needed to be recalled and a new test that needed to be sent out.

Those were critical days and weeks in the early part of the epidemic that were wasted where we had an opportunity to potentially identify what was then a relatively small number of people who had the infection through testing.

But by missing that opportunity, we failed to identify those people and provided them an opportunity to infect other people, allowing the virus to generate over a couple of generations before we started any kind of meaningful intervention.

SARAH BALDWIN: And what is the status of testing now? Do we have enough tests for a significant sort of catch-up to happen?

MARK LURIE: So you'd have to ask people who are closer than I am to the distribution of tests nationally. I think we have a very long way before we catch up. We're still in a situation where there aren't nearly enough tests available for all people who would need them. And so tests are essentially being rationed to certain populations be they health care workers, older people, or people with underlying conditions.

There was an interesting article in today's New York Times, one of the op-ed columnists for The Times reported on his own experience with the virus and like many people was told that they don't fall into the risk category to warrant testing. So they were sort of presumptively diagnosed. That is, a test wasn't done. But they had contact with a doctor who said, yeah, you probably have coronavirus.

So we're still in a situation where there aren't nearly enough tests to test a large enough proportion of the population such that we're able to effectively identify a large proportion of the current cases. Part of the reason for that is the initial bungled response where we lost many days, if not weeks, and tried to address the epidemic when tests were not and continue to not be readily available.

SARAH BALDWIN: Let's take a break from the US for a moment. We haven't yet heard a lot about Africa, including sub-Saharan Africa, where you've done a lot of your research and where you were watching this happen. Weren't you just there for several weeks?

MARK LURIE: Yeah, I was there for a few weeks. And I just got back over this past weekend.

SARAH BALDWIN: So you were watching the outbreak in the US happen from there. What makes the conditions in, say, Cape Town or South Africa generally especially concerning when it comes to the coronavirus?

MARK LURIE: So there's a few things that worry me in particular about the potential impact of the coronavirus in sub-Saharan Africa. First is that as the epicenter of the HIV epidemic and indeed of the tuberculosis epidemic as well, sub-Saharan Africa has an inordinately large number of people who are immunocompromised. And we know that this virus seeks people who are immunocompromised and does its most damage amongst people who are immunocompromised.

A small positive is that experts believe that HIV infection per se is not a risk factor for poor outcomes for coronavirus, but uncontrolled HIV is likely to be a factor. So what that means is that amongst people who have HIV, you have a proportion of people who are on antiretroviral therapy and are successfully taking their antiretroviral therapy.

They achieve a state that we call viral suppression, which is that by adhering well to their medicines, they are able to reduce the amount of virus in their bodies to a level that is essentially undetectable.

Amongst those people, experts believe that the coronavirus will probably not have a big impact. It's really amongst the people who are HIV positive, but who are either not on treatment or who are not successfully adhering to their treatment. Those are the people who are most likely to have poor outcomes from the coronavirus.

So the first concern we have is just the large number of people who fit into that category. Just a back of the envelope calculation, in South Africa with populations a little over 50 million people, we have over 7 million people with HIV infection. And probably somewhere around half of those are virally suppressed, which means that the other half are at very great-- are potentially at great risk of poor outcomes from coronavirus.

In addition, sub-Saharan Africa has historically suffered from poor health care systems that are even in the best of times often stretched to their capacity or beyond. And the kinds of surges that we're beginning to see of patients, say, in New York, which itself is not equipped to deal with those kinds of numbers, would be really catastrophic in sub-Saharan Africa in a health care system that is already highly compromised. So these are some of the things that we worry about in terms of the epidemic in sub-Saharan Africa.

On the other hand, while I was there, which is to say about a week ago, the South African president announced a kind of partial shutdown of the country. He did that when there were approximately 50 known cases. So the optimist in me hopes that South Africa was able to react strongly and importantly early enough that they have the potential to stave off a large-scale epidemic.

Since then, the number of cases has increased dramatically, again, partly because testing is being more widely rolled out. But just the night before last, the president announced a three-week essentially a lockdown on the entire country. So the fact that South Africa and some of the other southern African countries might have acted early in this epidemic gives them a huge step up.

SARAH BALDWIN: I hope you're right. That does give us hope. I wonder, though, what about people in areas where social distancing and physical distancing is not possible.

MARK LURIE: Sure. Just like New York is a highly densely-populated city, so too many African cities are large, very densely-populated places. I'm thinking, say, of some of the slums outside of Lagos or any major African city that one would-- that one could think of.

To what extent people will be able to self-isolate, that I think is something that we don't yet know but certainly a concern that one would have that in these very, very densely-populated places, self-isolation might be-- is going to be a very difficult thing for people to do. And that's likely to reflect in terms of kind of epidemic growth.

SARAH BALDWIN: Mark, should we be aiming to control the spread of COVID-19 and the coronavirus that leads to it or eradication?

MARK LURIE: So I think our immediate efforts have to be focused solely around control. Eradication is a long-term, highly-desirable goal. But it's going to take-- it can't be achieved without control. So we focus our first efforts on control. And those are things like identifying people who have the virus, isolating those people, and stopping the chains of transmission.

We can only achieve control, which I would define as a decreasing number of cases, we can only achieve that by those strategies of testing, isolation, and finding and isolating contacts of those who are infected.

Eradication is highly desirable but a much longer-term goal. Eradication would be defined as the elimination of all infections in a defined geographical area. And we're obviously a very long way from that.

Eradication probably will take effective treatments that we don't yet have. And it will probably take an effective vaccine that we don't yet have. And both of those things could be anywhere from many months to up to 12 or 18 months away. We haven't even started to control the epidemic in a meaningful way in the United States yet.

SARAH BALDWIN: Well, speaking of vaccine, a possible vaccine-- and this might be a dumb question-- are we envisioning a vaccine that's curative or that's prophylactic?

MARK LURIE: So not at all a dumb question. And vaccines could be either. They could be given prophylactically to people who don't have infection in the hopes that they-- that the vaccine renders them immune from infection, or they could be given to-- a different vaccine presumably could be given to people who already have infection. And that could reduce the number of poor outcomes.

Right now, when we talk about vaccine, we're really talking mostly about prophylactic. That would be something that's given to people who are uninfected and that offers protection when they're challenged by the virus. That's the most likely path. And that, I think, is where most of the energy in terms of a vaccine is currently being invested.

SARAH BALDWIN: I'm wondering is there-- are there any lessons from how the global community dealt with the HIV/AIDS epidemic that provide lessons for COVID-19?

MARK LURIE: Yeah, I would say two things. So wasted days mean that more people in the community are infected and able to spread to others. And sadly in this country, we dillied and dallied early on and didn't really intervene meaningfully in a very early way.

The second thing I would say that we learned from the mistakes of the HIV epidemic-- and we're seeing some of those same mistakes repeated-- is in the xenophobia and the blaming of others that is becoming prevalent today and seen frequently on the president's daily briefings where he says things like the Chinese virus or the foreign virus.

We know in HIV in the early years of the epidemic, people were eager to point fingers at others and to demonize those people with the disease. And these things set back our HIV prevention efforts dramatically. And we're seeing similar things happen today with coronavirus. With the president saying things like the Chinese virus and the foreign virus, these are things that are likely to stoke xenophobia and blaming of the other.

And they're going to have the exact opposite effect of controlling the epidemic. They're going to lead to more people infected, more xenophobia, more hatred, and when in fact the opposite is what we need. And the truth is that viruses don't respond to xenophobia. That's not a tried and tested intervention that's likely to have any positive impact. And yet, our leader still thinks that this is a good way to go.

SARAH BALDWIN: I'm wondering, Mark, what keeps you up at night these days? And also, is there anything that gives you hope?

MARK LURIE: What bothers me I think more than anything is that there are effective and ineffective ways to deal with this crisis. And sadly, at the federal level, we seem to be taking the ineffective way as much as possible.

So for a while, we did exactly what China did, which was ignore the epidemic and say that it's really not a big deal and it's about to go away. That's precisely what the president said. And during that critical window, we lost an opportunity to respond early.

Then the president told us that a vaccine would be ready soon. And in fact, we know that that's probably 12 to 18 months away and that's if things go well. So now the president is touting an unproven treatment. That is chloroquine. That's a drug that's often used for malaria and other things. And he's telling us that this is a potential silver bullet solution to the epidemic, but this isn't based on science at all.

And it's based on from what we can gather a anecdote that the president heard about somebody who took the drug and supposedly recovered combined with what he called a, quote, "gut feeling" that he has. So as a scientist, these things make me very concerned.

These are very important decisions that we have to make about the health and well-being of our country. And they should be made with strong scientific evidence. And so far, there's no scientific evidence to support that this chloroquine is going to be a magical solution to the epidemic.

And these actions have consequences. So we read today about an Arizona man and his wife. The man died and his wife's in critical condition after they ingested chloroquine phosphate, which is a cleaner that's used in aquariums but that contains similar drugs to-- similar active ingredients to chloroquine which the president has been touting.

We also know that there have been chloroquine-related deaths reported in Nigeria. And in the US, physicians are prescribing, in fact, overprescribing these drugs for themselves and their families, leading to shortages in some places for people who actually need those drugs and for the American Medical Association to call for an end to this practice.

So what keeps me up is the unscientific approach that we're frequently employing in this country, which is not going to have a positive impact on the epidemic and is in fact likely to do the opposite.

What do I see as reason for hope? To be honest, one has to look pretty hard for a reason for hope. Sure, South Korea and China and to some extent Italy appear to be reversing the course of the epidemic. And that gives us hope that with similar measures, we could do so in the United States.

But for the most part, most countries that are dealing with the epidemic are still on an upward curve, which is to say that the number of new cases continues to increase. And that's something that is of great concern and leaves us very little to get excited about, very few paths that we can point towards as ones that have been successful.

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SARAH BALDWIN: I do appreciate your candor and for such clear and helpful explanations of what the situation actually is and how grave it is. I really want to thank you, Mark. We overcame some technological challenges to do this interview remotely. And I want to thank you for that and for your time and expertise. It's been great talking to you.

MARK LURIE: Thanks for having me.

SARAH BALDWIN: This episode of Trending Globally was produced by Dan Richards and Jackson Cantrell. Our theme music is by Henry Bloomfield. I'm Sarah Baldwin. You can subscribe to us on iTunes, Stitcher, or your favorite podcast app.

If you like what you hear, leave us a rating and review on iTunes. It really helps others find the show. For more information about this and other shows, go to watson.brown.edu. Thanks for listening. And tune in in two weeks for another episode of Trending Globally.