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150,000 people in the United States have died 

after being infected with COVID-19. It’s a sobering milestone that comes at a time when an increasing number of states are seeing an uptick in infections and hospitalizations. 

What we’re experiencing now is something Minnesota epidemiologist Michael Osterholm has likened to a “

.” During a time of surging cases, he told NPR, contact tracing and traditional testing aren’t going to go far enough to slow down the spread. 

MPR News host Kerri Miller on Monday talked with Osterholm about the management of the pandemic, vaccine development and the possibility of additional lockdowns. 

On how to assess COVID-19 risks

To standardize COVID-19 tracking

A portion of this conversation has been transcribed and lightly edited for clarity. Listen to the full conversation with the audio player above. 

Several times you have compared the way the virus is moving through our population as the way a fire consumes wood. Why have you chosen that analogy?

Well, just to remind everyone, we really are in uncharted territories with a coronavirus pandemic. This is a novel virus that we've never seen a global outbreak or a pandemic with it before our previous experience has been with influenza pandemics when a new flu virus emerges.

In March and April, when it was being discussed: How might this move forward? What might it look like? Not a model — meaning the statistical analysis, which I find always troubling — but just a scenario, how might this happen?

Well, if we look at influenza pandemics, they have traditionally performed in a very similar way. There have been 10 of them in the last 250-plus years. And when the virus first arrives, it does travel around the world — even in the days of just sailing vessels — and causes illness for several months to up to five or six months, and then recedes for reasons we don’t know why.

In 2009, when we had the H1N1 pandemic, we saw it occur in the U.S. here in mid-March. Cases continue to increase through April into early May, and then just all of a sudden, just the bottom fell out of it, it dropped out. We didn't see transmission of any notable quantity in through all the summer until late August. Then all of a sudden it took off again, and by far the biggest wave we had. The biggest peak occurred in mid-September and early October. we were not trying to do distancing mitigation or any of that kind of thing back then. So this was really kind of the natural history of the virus.

So the question was: Is this what the coronavirus is going to do? Is there going to be a wave and then a trough and then a wave? In fact, by May, we could see that this wasn't going to happen. That in fact, there was going to continue to be this ongoing pressure of the virus out there, wherever it could. And it may be set off by time, meaning some places hit earlier than others. 

We had come up with a document that actually laid out these scenarios: One was [like] the flu; one was kind of a slow burn; and one was more of a rapid burn more like the forest fire. In May, we changed the scenarios, and said we’re now locked into this one: This one is just going to keep burning, where it's suppressed and put out it surely could come back again tomorrow if the embers are there and starts transmission.

As we talked about last time on the show, we need to achieve what we call “herd immunity,” before the virus transmission will slow down. This is where enough people in the population have either been infected by the virus and developed immunity that way or been vaccinated. And for a virus like this, it's going to take at least 50 to 70 percent of the population to be previously exposed or vaccinated to get that herd immunity. So we said: This thing is going to keep running. And it’s going to come and go and come and go and only with really active mitigation efforts will we ever slow it down. Our whole goal is to slow it down enough until we can get to a vaccine, where we can achieve protection that way as opposed to the disease itself.

In the beginning of the pandemic, a lot of us were following the news and there would be big headlines and breaking news every time some analysis came out from Oxford or somewhere else. It sounds like you've been troubled by that from the beginning. Why?

Well, first of all, I've had a number of graduate hours of statistics. And I realized that a lot of this is “black box” kind of work where assumptions are made, that can in many instances, not even be close to valid of what really happens. Some of the models are actually just based on previous experience, meaning if I have 1000 numbers in a row, I can predict 1001 number by looking at that sequence, which doesn't give you any sense about how this virus might change.

For example, as it did from the March-April peak to the June trough, and then took off again, models missed all of that. I've never believed that models were all that helpful. As I've said before, all models are wrong, and some will occasionally give you useful information. We've not relied on that and making any of our predictions at all. 

The kind of situation we see now was something we just said this is based on that scenario I said about the wood. Just think of a forest fire: If you suppress it substantially in a given area, and then you don't clean it up, you don't finish it, it's coming right back. That's the problem we're seeing right now around the country. You just have to assume everybody who has not been infected with this virus is vulnerable to being infected. And if we don't take steps to stop that transmission — either by limiting how you have contact with people or having a vaccine — it's just going to keep marching right along until it finds us.

Could you have seen this coming, moving out of the cities moving into more rural areas, and then putting some of these places that thought they were over the worst back at risk?

I think if you were to go back and look at my previous interviews on your show, including one in April, I actually mentioned at the time that there would be no red and blue states. By the time this was done, they'd all be COVID-colored states.

So, we knew last March and April, that this was going to be doing exactly what it's doing right now. And so I'm somewhat concerned that the public health community seems now to at least from Dr. Deborah Birx — her comments — discovering what we all should have been aware of months ago, and doing something to try to put that message out.

I've heard time and time again from Minnesotans who have been upset with my comments about, “Well, it's not a problem here.” I’m from rural Iowa. I get that. And I kept saying, “I don't want to make this sound like I'm wishing anything bad on you, but just take time. It's coming. It is coming, and it will be there.” And right now, some of our hottest transmission areas in the state are in Greater Minnesota.

That's the challenge we've had is some people thought last March, when so much of the activity was initiated to try to slow down the spread that it was going to be everywhere all at once, and it's not, but over time, it will be.

From a tweet: Could Dr. Osterholm talk about the U of M's engineering study on heating, ventilating and air conditioning (HVAC)?

Could Dr. Osterholm talk about the U of M's engineering study on heating, ventilating and air conditioning (HVAC)?

One of the things that we're unfortunately having to deal with is a lot of misunderstanding about what we call aerobiology. When you and I talk — or for that matter, when we're just breathing — we actually exhale out lots of particles. Imagine these particles, from a standpoint of vision, range from BBs to bowling balls, and they’re consistent. Meaning that they just keep gradually getting a little bigger. When you and I cough and sneeze, that's when the bowling balls typically come out. They’re the ones that fall short, you know, just mere feet away. And clearly the aerosols — these little tiny particles — float and float and float. That's what we've really been concerned about. 

This is where some of your listeners may have heard a couple of weeks ago, a group of international experts, 239 of them, sent a letter to the WHO saying: Come on, get with it guys, aerosols are really important with this transmission. And it accounts for why we see some of these very large outbreaks.

How coronavirus might travel through the air

What we know about transmission of COVID-19

If you want to understand what an aerosol is, next time you see sunlight coming through the window in your house and you see all the dust floating in the air, that's an aerosol that's floating. Or if you're walking down the street and all of a sudden you smell cigarette smoke, and it turns out somebody is 40 feet in front of you, that's an aerosol. 

So what the [person] is asking about: What happens with recirculated air and how much do you have to recirculate? One of the things we've been trying to explain to people is this is not like an infectious disease tag, where if I walked by somebody, I get infected ... Rather, it is how much time I spend in an area where these aerosols are floating, and occasionally, if I'm right face front to somebody, these large droplets come at me. And that's where we're all working to try to find out just how long you have to be in those kinds of settings to actually take in enough of the virus.

So, the study at the university was one of those ones that said: Unless you're really moving a lot of air, this is a problem. I get so many questions from choir directors. Can we just, you know, if we put all our people together, we space them out? And my church has an air exchange of once per hour. And we’re talking about 12 times per hour, probably to exhaust off those viruses. That's the kind of work we're doing right now to try to understand that.

Caller question: As a physician, I don't doubt what you're saying about the serious seriousness of this disease. But what I also worry about is the economic impact of closed down and where do you draw the line? How do you figure that out?

We think about that all the time. The challenge we have is: If you look at what’s happening right now … with this kind of background level in the community, when it takes off, there is so much economic damage that occurs just from that. Take a look at what's happened in the southern states.

I don't think most people realize it. But right now Minnesota is on track — if something doesn't change — to become one of the southern states Sunday reported, basically, the most number of cases were reported this year. We were at a peak of 728 cases reported on May 24. We dropped back down to 320 cases on June 19. Everybody took a sigh of relief. Sunday, we had 759 cases. When that starts to happen, and things begin to shut down on its own, you can't open schools, you can't basically have many of the same services. Your hospitals are overrun. At that point, that's a huge economic cost.

So the challenge is how do you find the right place on the break? And what we have found from countries around the world, who have sure led the way in ways we haven’t — or if you even look at the state of New York — which was a house on fire in March and April — now, they've had four straight weeks of flat cases. They had days last week with no deaths in the whole entire state. What they did is they applied the brakes only after they got the numbers driven down to a manageable level in which they could do more testing and contact tracing. That doesn't mean they couldn't have a flare up tomorrow, but they've demonstrated what you can do to kind of find an equilibrium with this virus.

That's what we're all trying to figure out is how do we get that there? But I'll tell you right now, if you're in any one of these states — Minnesota included — right now testing and tracing is not going to have a material impact on our cases. It is like trying to plant your petunias in a Category 5 hurricane, it isn't going to happen.

And so one of the challenges is: How do you get those numbers back down? How do you get them down and then keep them down once they're there. And that's the challenge we're up against.

We all talk about 1918, and the challenge of what happened with the swine flu pandemic back then. Well, in April of this year, if you look at what was happening then in the United States with deaths, put it in context: On March 1. COVID-19 was not in the top 100 causes of death in this country. By April 18-19, it was the No. 1 cause of death in this country day after day after day. Nothing has done that to us since swine flu in 1918. Nothing.

Now deaths came down in July. We kept saying: Wait a minute though, deaths are following case numbers by two to three weeks, because that's how long it takes for people to actually get infected get really sick and then die, unfortunately. Wait until August comes, case numbers are going to go way back up. 

In the period of around that April 19 time period, we were exceeding about 1,500 deaths a day in this country. Well, you know where we're at right now? We're seeing now 1,226 deaths on a seven-day moving average. We're almost back to where we were soon This will be the number one cause of death in the country again.

You just said that Minnesota is on track to be one of those southern states. What did we miss in that moment of opportunity when cases were down that we should have been doing? How did we screw up the opportunity?

I’m not sure I take your characterization that we screwed up. I think the challenge has been … people have a sense that we were over this. There was a sense of invulnerability that occurs in our younger adult population that has been part of the feeling of those bars and restaurants have been a major problem.

Indoor air. I can’t say that enough times, indoor air. We saw this explosion there and people said, “Well, you know, young adults don't really get that sick, you know, they don't die from it,” which isn't true. They do die. Not as nearly as frequently as older individuals or people with underlying health problems. And now we’re seeing the spillover. I can tell you of far too many examples, where Father's Day was a disaster. Not at that day because a family all came home, but nobody realized somebody of the younger adult population was infected and transmitted to family members and mom or dad are now dead because of that Father's Day event.

We're now seeing the deaths rise nationally — both in younger populations to some degree, but also in the older population where it's spilling over. And this is going to just keep playing out around the country over and over and over again.

My worse nightmare right now — I’m going to get a ton of emails and just horrible phone calls — I am absolutely frightened by the prospects of this week in Sturgis. 275,000 Americans are going to descend on that town. There are going to be a lot of indoor bars. There are going to be an older population relative to young adults, which are going to be put them at much higher risk. They're going to be there for nine days, which would just guarantee that transmission that occurs at the beginning will only be amplified through the whole time period. And we’re operating as if nothing’s new. I’m promising you right now with all the pain I can say, that come August to early September, Sturgis will have one hell of an imprint on this country.

Sturgis may be 'recipe' for spread

The problem is that it isn’t just they all come together and congregate in this town in South Dakota, but then they go back to their own communities, right? And they take the contamination with them.

You know, I just, I can't say this loudly enough. Right now over 1,400 health care workers in this country have died from COVID-19. Not all of them were health-care-related, some of them got it in the community, but many were related to their work in the health care setting.

So just understand, when you get infected, you're expecting people to take care of you. You're expecting if you need hospitalization, someone will be there to hold your hand. Won't be your family members because they won't be able to get in, but someone will be there. The brave doctors and nurses and support staff — respiratory therapists, laboratories, even the janitorial staff in these ICUs — are nothing short of heroes. So every time you are an infection in this community, just remember you may be putting somebody else’s life at risk to when you have to go be hospitalized. Because as much as we try, we’re still seeing transmissions in our ICUs. I don’t think most people think about that.

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