RACHEL MARTIN, HOST:
Health officials are reporting a huge jump in the number of coronavirus cases in China's Hubei province. That comes as scientists there have changed the definition of who has the disease now known as COVID-19. With this new definition, the number of cases worldwide now stands at about 60,000. More than 99% of those cases are in China. NPR's science correspondent Richard Harris is with us in studio. Richard, thanks for coming in.
RICHARD HARRIS, BYLINE: Sure. Good morning.
MARTIN: So does this new figure represent an expansion of the disease, if we can call it that, or simply a change in how it's being defined?
HARRIS: It's mostly a change in the definition. But changing the definition of a disease does make it harder to track trends and to really understand what's going on beneath the surface, right? So we know the jump from last week to this week is not actually the result of a huge change in how this disease is progressing.
MARTIN: So what's the rationale? Why did the Chinese government decide to change the definition in the first place?
HARRIS: That question came up yesterday at a press briefing at the World Health Organization in Geneva. And WHO scientist Sylvie Briand helped explain what's going on.
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SYLVIE BRIAND: First of all, what is important to understand it's normal during the course of an outbreak to adapt the case definition because we need to be very close to the reality to monitor the disease, how it is unfolding.
HARRIS: And in the earliest disease - in the earliest days of this disease, the virus hadn't been identified, so all the cases were essentially defined by clinical symptoms, like pneumonia and so on. Here's Dr. Briand again.
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BRIAND: The situation is evolving. So when you have few cases, you have a very sensitive and specific case definition because you really want to tackle each and every case. When the situation is evolving, you change your definition just to make sure that you can monitor the disease accurately. And this is what they've done recently, changing the case definition to incorporate mild cases.
MARTIN: So she's saying there it's now going to incorporate mild cases. I mean, what effect is that going to have other than obviously having more cases to report.
HARRIS: Right. Well, in the short run, it causes some confusion because you can't simply compare last week's numbers to this week's numbers and get some sense of a trend of the disease. But in the long run, it will actually be helpful because health officials really do need to control those mild cases, too, in order to keep the disease from spreading. So going forward, we could well have a better sense of how the disease is progressing. It's also the case that once you've included all those mild cases, it will push down what's called a case fatality rate, which is the number of deaths per disease.
MARTIN: Incidence, yeah.
HARRIS: Yeah. So you don't change the number of people who die when you change the definition of who's sick. But if you include all of these additional people...
MARTIN: The rate will go down.
HARRIS: The rate goes down, yeah. There's about 3% right now, something like that, in China. But that may be an inflated number once you put in all of these other cases.
MARTIN: Yeah. So let me ask you this. There's been a lot of frustration that China hasn't been letting in international scientists, including scientists from the U.S., so they can see for themselves the data behind all of these numbers. What can you tell us about that effort?
HARRIS: Well, China has finally granted WHO some access. The WHO sent three experts to scope out the situation earlier this week, and they're trying to figure out exactly what their full team would do. The CDC hopes to be part of that delegation, but that still hasn't happened.
So, you know, there has been a lot of suspicion that China isn't telling the whole story. But the W.H.O. has been pretty adamant that China has been very helpful, especially when it comes to controlling the spread of the disease outside its borders - witness the fact that less than 1% of all of those cases are elsewhere. So at that news conference yesterday, WHO scientist Mike Ryan pointed out that the new case definition is actually a step toward that transparency.
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MIKE RYAN: This is not an attempt to ignore cases; it's an attempt to widen the net and include milder cases and all lab-confirmed cases, regardless of the symptoms.
MARTIN: So why aren't they just counting the number of people who have tested positive for the new coronavirus?
HARRIS: Yeah, that would be ideal if the test were completely reliable and if they had enough of the test kits to go around. But we've seen reports that the tests in China have been in short supply and of questionable quality. It's generally run from a nose or throat swab. And in some cases, when you swab like that, you really don't get the virus necessarily; it could be deeper in the lungs. So even a perfect test may not pick everything up. But, you know, that's why they're trying to expand. They'd rather include cases that are too big.
MARTIN: Mild.
HARRIS: Mild, exactly. So...
MARTIN: All right. NPR's Richard Harris for us on the continuing machinations of the story of the coronavirus. Thank you so much, Richard.
HARRIS: Anytime. Transcript provided by NPR, Copyright NPR.
