What being sick and symptomless means with the coronavirus

Read the Full Transcript

• Hari Sreenivasan:

  When it comes to COVID-19, there has been a great deal of discussion about whether or not people are asymptomatic and what that could really mean when it comes to contracting and spreading the virus. I recently spoke with ProPublica health reporter Caroline Chen who delved into the data to find out more.

• Hari Sreenivasan:

  Caroline, let's start talking about how do we figure out who to test, who to treat, especially if there is this possibility that we are now flattening the curve. How do I know if I'm somebody who's already had it? And if I'm asymptomatic?

• Caroline Chen:

  So I think that there are two concepts here. A true asymptomatic person is somebody who never had symptoms at all. And there's another word that I'll introduce, which is pre-symptomatic, which is somebody who at the time they were tested and was positive, didn't yet have symptoms, but then maybe later on had a cough or a fever. And so we now know that there are both types of people, more commonly maybe that there are pre-symptomatics. And I think it's really important that we be testing people, you know, with diagnostic tests so we can find these people out there because we don't know. People can start transmitting the disease before their symptoms turn up. To your other question, which is can I find out if I had been infected? That requires a different type of test. That's an antibody test that's done with blood.

• Hari Sreenivasan:

  If we don't know yet exactly when people start transmitting the disease, that makes it incredibly hard to try to say, OK, This group of people, you need to stay home. This group of people you can walk about in society. Right?

• Caroline Chen:

  We now know, in fact, that people probably have what's called a really high viral load, which means that they have a lot of infectious virus early on in the course of their disease, maybe even before they've started to show symptoms. And so that's helped make this disease and this virus particularly contagious.

• Hari Sreenivasan:

  Because most of us in the beginning when this started, we were told if you're showing any symptoms, stay home. And we did as best we could. Obviously, if I didn't have a cough, I didn't feel feverish, if I didn't have all those aches and pains… I said all right, well, let me just go to work. And then what happens if four days later I get this? So those first three days when I was going to the office, I might have been spreading it to everyone else?

• Caroline Chen:

  Yep. That, unfortunately, is now what we think. And this is why, you know, the W.H.O. and the CDC are all saying that social distancing really, really matters. And that six foot distance really can make a difference. So I talked to a lot of scientists and I said, well, you know, we've been told, you know, coughing and sneezing, you know, that's how droplets get transmitted. And this image was given to me by a virologist, Angela Rasmussen at Columbia. And she said, you know, on a really cold day, when you step outside and you're, you see that fog in the air? She said that's respiratory droplets. And that's why people keep saying six foot distance, six foot distance. Because if I'm already infected and I'm not yet maybe actively coughing, I'm still producing respiratory droplets and I could infect someone without even realizing it.

• Hari Sreenivasan:

  And that's one thing if you're outside. It's another thing if you are in a space that has why the recycled air or not much airflow.

• Caroline Chen:

  Yeah. And so, you know, a lot of the people that I've been talking to, the experts say that density matters, right? So if you're in a packed subway car where everybody's kind of breathing on each other, you know, it's much more likely that disease will be transmitted there than if you're in the open air.

• Hari Sreenivasan:

  Were any of the scientists surprised by anything that they learned? I mean, maybe how this virus is behaving differently than previous viruses that they know about?

• Caroline Chen:

  Yes. So one of the things that I just mentioned earlier, this concept of viral load, which is when are you most infectious in the course of your disease? With this virus, you're probably the most infected, right, early on at the start of your disease course. Maybe even before you start being symptomatic was, has been a surprise.

• Hari Sreenivasan:

  And it's also going to matter, about how we and when we get back to life as normal.

• Caroline Chen:

  Because we know that asymptomatic transmission can happen. We're going to need to utilize both types of tests. The diagnostic tests to find out if someone has an active infection and the antibody test to find out if someone had a previous infection. To find out both where the infection where the virus is spreading and which people have been previously infected. These tests are going to be key to help public health officials figure out what to do.

• Hari Sreenivasan:

  Do they have any idea on when my body would form antibodies or how long those antibodies would last?

• Caroline Chen:

  Yes. These are the questions that are being figured out right now by scientists. And so at the point you have just been infected, the thought is that the antibody tests should not be used like a right then because your body is still forming those antibodies to fight off the infection. And so, but they should last at least for weeks and months. And so you would be able to then look back months later and see whether or not you had those antibodies. The open question right now is what amount of antibodies you need in your blood to give you immunity. These tests are already being developed, already being made. But I think there's a lot of work being done by scientists to really study, you know, the amount in people's blood and what kind of immunity that actually conveys.

• Hari Sreenivasan:

  Caroline Chen of ProPublica, thanks so much.

• Caroline Chen:

  Thank you for having me.