OPINION

When will social distancing end? Will opening up contribute to second wave of disease? Scientist Marc Lipsitch answers our questions.

USA TODAY

USA TODAY

As daily coronavirus-related deaths reached new highs in New York and nationally, USA TODAY’s Editorial Board spoke Wednesday with Dr. Marc Lipsitch, one of the nation’s leading epidemiologists, about the state of the pandemic. Lipsitch is a professor of epidemiology at the Harvard T.H. Chan School of Public Health and director of Harvard’s Center of Communicable Disease Dynamics. Questions and answers have been edited for length and clarity.

Q. What is the trajectory of the coronavirus, and where are we headed?

A. Assuming that we're detecting something like one-tenth of all the cases, or one-fifth or something like that, and assuming that protective immunity occurs after most cases, then we're near the beginning in the sense that most of the population in the country remains susceptible. The goal of the current set of restrictions is not to solve the problem, but rather to solve the acute problem of keeping the numbers of patients from exceeding health care capacity.

Q. Are the restrictions working to do that?

A. Some evidence is beginning to accumulate that we may be able to accomplish that in many places. New York is already near the maximum it can handle, and the question is whether it will come down. There's maybe some hint that's happening. And in other places we'll see whether it goes up more and then peaks in the next week or so, or whether it keeps on going up and exceeds capacity in various places.

Q. Then what?

A. If that works out well, then there's the big question of what do we do next? Because if we relax restrictions, as we saw in the 1918 pandemic, and as we've seen probably in China now, there's every reason to expect a resurgence of cases and we're back in the same problem. On the other hand, keeping these restrictions in place is economically disastrous. Under this scenario, we're in a dilemma, and I don't think anyone has found a good answer.

Q. So what do we do?

A. Some ideas out there are probably worth trying, including essentially trying to bring cases down in each locality to a point where they can be controlled individually. There is a contingent of people — a number of them at my university with whom I disagree very, very strongly — who are saying that we need to implement Chinese-style out-of-home mandatory quarantine and isolation as part of that response strategy for containment. The evidence that that is necessary is slim, and the evidence that it would be acceptable in the United States is nonexistent. But there is that view.

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Q. Wuhan, the original epicenter, is opening up. Do you find China’s reported numbers — about 83,000 confirmed cases and 3,300 deaths — to be credible?

A. I don't think they're credible in terms of actual number of cases. And I don't think that they even captured all the deaths, because they probably missed deaths at home and things like that. There's clearly underdetection. Whether they were hiding things, I don't have any more insight, and probably less, than many of you. It doesn't seem to me crazy that those are the best numbers they can come up with, but I'm open to persuasion that there's funny business going on.

Q. In the hot spots like Wuhan and northern Italy, 3% or 4% of the population had confirmed infections. But you and other epidemiologists talk about 40% or 70% of the entire population getting infected. Can you explain that gap?

A. There's a first wave, and then there's the whole epidemic. A lot of the confusion is premised on the misunderstanding that if you control the epidemic once, then you're done. There's no reason to think that. Wuhan is starting to see resurgence of cases as they let up, and in 1918, we saw it all over the country as restrictions were lifted. So 40% or 70% is the number that you need to have immune before viral transmission stops on its own. The number that get infected under very intense control measures is the number that happened before those control measures fully take effect. Those are two different numbers.

Q. Do we know that if someone has been infected, they will be immune? And if we don't know that, how does this work in second and third waves?

A. We don't know that yet. We do know for other coronaviruses that there is a period of immunity that's partial but quite strong. The thing that matters for control of the epidemic is the proportion of the population that's immune, or at least immune enough so that they're not going to significantly transmit infection.

That's the number that we have to get high enough, either through vaccination or through infection.

Q. Could that number already be higher than we think?

A. One possibility is that there are just a huge number of undetected infections, many of which may produce immune responses. We may just have more “herd immunity” than we know. There are anecdotal hints about that, but no firm data yet. The flip side of it is that if some significant proportion of those infected don't get immune, then that subtracts from the immune fraction of the population. We really, really need serologic studies (to see if people have been infected and have antibodies).

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Q. How protective is the immune response?

A. We and others are trying to study that, but that's actually kind of tricky to do. Someone will figure that out, but it will be a while.

Q. Do the nation's governors deserve the greatest amount of the credit so far for their decisive stay-at-home actions?

A. The Northeastern governors have been very aggressive. The Washington state governor has been very aggressive. The California governor has been very aggressive. And on the flip side, Texas and Florida, probably among others that are less notorious, have been quite a bit less aggressive. So I think the successes are not coming from a central source. The federal messaging has been confusing at best. So I would give a lot of credit to the governors who have been aggressive.

Q. How will we know when it is safe to discontinue stay-at-home orders?

A. That's a great question, and I think the serologic surveys will be critical in doing that, because that's a necessary piece of the puzzle to understand how many people have been infected. The second piece, once we have those serologic studies, is figuring out how protective immunity is. We don't know whether it will be possible to distinguish someone who is functionally immune from someone who has an immune response that's not that protective. We hope that it will be possible. But that's an open scientific question right now.

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Q. How long will it take to answer that question?

A. I hesitate to say this, because I understand that it's economically and otherwise not really acceptable, but from the standpoint of trying to keep cases under control, I don't see an answer coming until at least the next month or two about it being okay to reopen. There may also just be so much fatigue that places will try it, and then they'll see the consequences. … Waiting until the ICU is overwhelmed again is not a good policy. It is a disastrous policy.

Q. Do you know of a plan for these serologic surveys? Are you involved in that?

A. In a high-functioning environment, this would be mainly the project of the CDC (Centers for Disease Control and Prevention). And I think that the CDC has begun to do, or at least plan, some of these surveys.

Q. How about the states?

A. I've been on a large team of really extraordinary people that are trying to do this in a comprehensive and strategic way. So I think Massachusetts will be one of the first. I think New York will be one of the first, and probably some other states that I don't know about.

Q. The CDC seems to be largely absent from the public communication effort. What effect does that have?

A. I think it's very unfortunate. I think Americans trust the CDC because they see the professionals there as apolitical and trustworthy and trying to protect health. I was there for a brief period in the 1990s, and I've worked with them since then, and that's what they are. Having filtered messages coming through politicians is much less trustworthy than having physicians and public health professionals telling what they know.

Q. Why is that?

A. The CDC, as a scientific organization, is well placed to say, “This is what we know, and this is what we don't know.” Politicians don't like saying what they don't know. Every crisis communication expert I've ever talked to says you need to hear both. People need to hear both, because then when the knowledge changes, it's not a surprise, and it doesn't feel like it's a reversal or something fishy going on. It's just scientific knowledge changing as definitely happens in a crisis like this.

Q. Polls show political differences in how people perceive the threat.

A. We're all vulnerable to the virus. It doesn't matter what party we vote for, or what church we go to or don't go to. It's a virus. And to the extent that people can get messages that are not mixed with politics, that's a whole lot better for helping them to protect themselves.

Q. What are the biggest unknowns?

A. To me, the enormous questions are about immunity. How much is there in the population now? How many of those people didn't even know they were infected? How protective is it? And then for the potential vaccine, how protective will immunity be? I think immunity is what's going to get us through to the other side. And that's the part that's still the biggest uncertainty.

Q. So how long will people have to hunker down?

A. It's not a scientific choice only. It's ultimately a political choice, and science is one input. I hope it's a very important input, but if a governor decides to lift these restrictions, there's not much that can be done other than to watch the consequences and kick the governor out. The question is, can we endure the consequences of them long enough either to get a vaccine or to let the cases accumulate more slowly so that we get towards herd immunity naturally? But that's a slow process.

Q. How important is testing capacity to the decision about reopening?

A. I think serologic testing capacity is probably even more important than viral testing capacity for making that decision. But viral testing capacity is going to be necessary for trying to control the infections that will inevitably spring up as restrictions are lifted.

Q. Does the country have the viral testing capacity that it needs?

A. Nowhere near. Nowhere near. I mean, it's been a debacle, and it's now almost what we need for the sickest patients and health care workers. But even locally here, there are intense shortages of swabs. If you can't swab people, then you don't have tests. It doesn't matter how good your machines are.

Q. Why has the testing rollout been so hapless?

A. It's partly hapless because there's not a strategy. Nobody has articulated, if we come out of these restrictions, how are we going to keep a lid on the cases that begin to emerge? And there are many challenges to doing that if you have good testing, but it's pretty clear that you can't do it if you don't have the testing.

Q. So how do you see things playing out?

A. If I had to make a prediction about how the interaction between social and scientific and public health factors will play out, I think there's going to be fatigue at some point. Some places are going to let up either after they've controlled the first peak or before they've controlled the first peak. Cases will reemerge, and because people are so tired of social distancing, it will take until the intensive care units are overwhelmed in that place to get people to crack down again, and then there will be some cycles of that. There are ways to try to avoid that, but they all involve this very long and destructive process of social distancing. It's easy to say as the public health person, this is what we need to do for public health. But I'm acutely aware that there are also other considerations, and I don't see a really good answer.

Q. Is there evidence the hot, humid weather in the summer will suppress this like it does other coronaviruses?

A. I think it will suppress it to a degree. The decline of coronaviruses, of all the winter viruses in the summer, is an interplay between running out of susceptible people to infect and having the conditions become less favorable. And when you have tons of susceptible people still around to infect, the virus can survive in less favorable conditions. It would slow the growth rather than bringing the number of cases down by itself. That's our best guess.

Q. Is there more of a threat to younger people than we originally thought?

A. You're right that the messaging has been more focused on the old and those with underlying conditions and probably missed a lot of opportunities with the younger crowd. There needs to be caution, because they do have a risk, even though it's a lower risk.

Q. What about the idea of sending younger people back to work first?

A. I don't think this is a great idea, but there is a school of thought that (this) would be less destructive than the alternative. The problem is that those people have parents and siblings and others that they can infect. I'm not sure that it's a very feasible option, but it may be the best option that we have, if we decide that staying closed for extended periods is not acceptable.

Q. Why is the virus hitting minority communities harder?

A. Underlying health disparities are well established. Hypertension and other disparate risk factors are going to be part of the problem here. It's also an economic issue. Density of housing is clearly a risk for transmission, and so the interaction between race and ethnicity on one hand, and income on the other means, there's that aspect as well.

Q. Are prisons a breeding ground for the disease?

A. Overcrowded prisons are a problem and a health hazard. The idea that it's better to have it all bottled up in a prison, and not let those individuals out into society, is kind of missing the point. Prisons have guards, prisons have kitchen workers, prisons have lots of people who are in contact with those prisoners. And the idea that it's better to just keep it in there is, apart from the inhumanity of it, also just wrong.

Q. We've long heard epidemiologists talk about “the Big One.” In your view, is this the Big One, and how does it compare with past pandemics?