Public Health Experts Encourage Social Distancing To 'Flatten The Curve' Of Infection

NPR's Ailsa Chang talks with Drew Harris, population health expert at Thomas Jefferson University, about what it means to "flatten the curve" when it comes to curbing the spread of coronavirus.

ARI SHAPIRO, HOST:

As the coronavirus spreads in the U.S., more people are working from home. More schools are holding classes online. More events are getting canceled. It's all part of an effort to do what's called flattening the curve.

AILSA CHANG, HOST:

Here's Dr. Anthony Fauci explaining this concept at the White House yesterday. He's the top infectious disease expert at the National Institutes of Health.

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ANTHONY FAUCI: If you look at the curves of outbreaks, you know, they go up big peaks, and then they come down. What we need to do is flatten that down. That would have less people infected. That would, ultimately, have less deaths.

CHANG: Well, to explain exactly what it means to flatten the curve of infectious diseases, we're joined now by Dr. Drew Harris. He researches population health at Thomas Jefferson University in Philadelphia.

Welcome.

DREW HARRIS: Thank you for the opportunity.

CHANG: So I want to help listeners visualize this graph that you first shared on Twitter about - what? - two weeks ago. I see two curves here. There's this red curve that's really tall and really steep, like a mountain. And then on top of that, there is a blue curve that's, like, more gently sloped up, and then there's this gradual, long slope down. Why don't you go ahead and explain the red curve first?

HARRIS: Sure, so these curves are, essentially, representing the number of new cases that occur over a period of time. So the higher the curve - that higher peak curve...

CHANG: This is the red curve.

HARRIS: The red curve is showing us that we are seeing a significant number of cases in a very short period of time. If you think of the - our health care system as a subway car - and it's rush hour, and everybody wants to get on the car once, so they start piling up at the door. They pile up on the platform. There's just not enough room in the car to take care of everybody, to accommodate everybody. That's the first curve, if you will. That's the system that is overwhelmed. It just can't handle it, and people wind up not getting services that they need. If we, instead, spread out those cases so that everybody on that subway car doesn't show up at the same time but, instead, shows up at different times, then that car can accommodate the right number of people but over a longer period of time. So the whole idea is to flatten that curve, make sure that not everybody shows up at an emergency department door at the same time.

CHANG: OK. But to take your metaphor of the subway one step further, you're assuming with this flatter curve that people will still need to get on the subway. In other words, you're assuming that we're not going to see a quick end to the spread of the coronavirus, that people will still continue to get infected.

HARRIS: Right. Just today, Angela Merkel announced that they're expecting that 60-, 70% of Germans will be getting - coming down with this virus. But if they all came down with it at the same time, the net system is overwhelmed.

CHANG: Right.

HARRIS: And we're seeing that in Italy at the moment. But if, instead, you can delay that time when you get that virus a few days later or a few weeks later, a few months later, then the system can adjust and accommodate all the people who are possibly going to get sick and possibly need hospital care. Now, it is possible that we will see fewer cases because you're less likely to be exposed to the disease any particular time. And maybe that time will be so far in the future we'll have a vaccine, in which case you'll be protected against the virus in the first place.

CHANG: Now, I understand these two curves - the steep curve and the gentle curve - that they actually played out during the 1918 flu pandemic. Can you tell me about how that worked out?

HARRIS: Well, it didn't work out very well for Philadelphia because they decided to hold their bond parade for World War I bonds when the public health authorities were telling them, this is not a good idea because we're seeing flu spread in the community. So they brought hundreds of thousands of people together for the parade. And within 48, 72 hours, thousands of people around the Philadelphia region started to die. On the other hand, St. Louis - they went with a different strategy, and they really tried to limit the travel of people and implement public health 101 - isolating and treating the sick, quarantine the people who have been exposed to disease, closing the schools, encouraging social distancing of people and, of course, encouraging hand hygiene and other individual activities. And a much smaller percentage of people died as a result of that particular outbreak.

CHANG: Some lessons even more than a century old are still worth learning.

HARRIS: Absolutely.

CHANG: That's Drew Harris. He's an assistant professor at the Thomas Jefferson University College of Population Health.

Thank you very much for joining us today.

HARRIS: It was my pleasure. Thank you.

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