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Why The Death Rate From Coronavirus Is Plunging In China

Mar 3, 2020
Originally published on March 4, 2020 9:30 am

When it comes to the spiraling global coronavirus outbreak, scientists are still trying to pin down the answer to a basic question: How deadly is this virus?

Estimates have varied widely. For instance, at a Feb. 24 news conference in Beijing, a top Chinese health official, Liang Wannian, said the fatality rate for COVID-19 was quite high.

"Between 3 to 4% of patients have died," said Liang.

Then he added a twist. Outside of Wuhan — the city at the epicenter of the outbreak — the death rate in China has been much lower: about 0.7%. That's fewer than 1 fatality per 100 cases.

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Similarly, a study released by China's Center for Disease Control last month found that if you factor out all the data from Hubei province, where Wuhan is located, the fatality rate in the rest of China drops to 0.4%.

Why such a big difference between Hubei and the rest of China?

At a news conference the next day, Dr. Bruce Aylward — who had just concluded a fact-finding mission to China for the World Health Organization — pointed to three likely factors.

First, said Aylward, is that Wuhan suffered from being the first place where the new coronavirus surfaced. "Wuhan started fast and, and early. People didn't know what we were dealing with. We were learning how to treat this."

The more patients medical staff saw, the more they could start identifying what kind of supportive care made a difference. So by the time patients started showing up in hospitals in other provinces, doctors and nurses there had a lot more information about what it takes to keep patients alive.

Hospitals in the rest of world will likely also benefit from that knowledge.

The second reason for the higher death rate in Hubei "was just the sheer scale of the numbers," said Aylward.

Hospitals in Wuhan were flooded with thousands of sick people. That stressed their capacity to provide the kind of round-the-clock intensive care needed for a patient with a critical case of COVID-19.

Elsewhere in China the caseload was much lower.

The implication for other countries: It's worth trying to at least slow the pace of an outbreak with measures to keep the number of patients from overwhelming local hospitals.

The final factor, says Aylward, "At the beginning of this outbreak remember, people were finding severe disease. And that's why the alarm bells went off."

Those early severe cases made COVID-19 look like a much bigger killer. It was only after officials in China stepped up surveillance that they started uncovering many more mild cases (people with symptoms such as fever and dry cough but limited or no pneumonia).

All of this may also help explain why over time the death rate for COVID-19 has steadily dropped.

According to the China CDC study, among patients whose symptoms started between Jan. 1 and Jan. 10 the death rate was 15.6%. But it was just 0.8% among those who didn't get sick until Feb. 1 to Feb. 11.

That pattern of progressively dropping death rates is one we're likely to see in other countries.

In other words, there's a good chance the fatality rate in nations with good health systems will end up being a lot lower than what was first seen in China.

Still, it's worth noting that even after China got the death rate down to 0.7%, or even 0.4%, that's still about four to seven times greater than the death rate for seasonal flu. (The rate for the flu is about 0.1% — or 1 in 1,000 patients.)

Also, the China CDC study shows that for coronavirus patients ages 70 to 79 the death rate more than triples. For those older than 80 it's more than six times as high.

Anna Yeung-Cheung, a microbiologist at Manhattanville College in New York, says she also worries about health workers.

Yeung-Cheung, who is originally from Hong Kong, notes that many doctors there died during the SARS coronavirus outbreak of 2002-2003. And hundreds of Chinese health workers have been sickened in the COVID-19 outbreak — possibly, at least in part, because they were working so hard, she says.

Sure, says Yeung-Cheung, "They're young. But we need to take into account the stress that they are undergoing. This is stress to their body."

Copyright 2020 NPR. To see more, visit https://www.npr.org.

ARI SHAPIRO, HOST:

There are now nearly a hundred cases of coronavirus in the U.S., a number that is expected to grow. Scientists are still trying to pin down the answer to a key question - how deadly is this virus? While estimates have varied, evidence does suggest that the fatality rate in the U.S. will be lower than what we're seeing in China. NPR's Nurith Aizenman explains.

NURITH AIZENMAN, BYLINE: At a recent news conference in Beijing, a top Chinese health official, Liang Wannian, said the fatality rate for COVID-19 was high.

(SOUNDBITE OF PRESS CONFERENCE)

LIANG WANNIAN: (Non-English language spoken).

AIZENMAN: "Three to 4% of patients of have died."

But then, Liang added a twist.

(SOUNDBITE OF PRESS CONFERENCE)

LIANG: (Non-English language spoken).

AIZENMAN: "Outside of Wuhan, the city at the epicenter of the outbreak," Liang said, "the death rate in China has been much lower - about 0.7%."

Why such a big difference between Wuhan and the rest of China? At a later news conference, Dr. Bruce Aylward, who just concluded a fact-finding mission to China for the World Health Organization, pointed to three likely factors. No. 1...

(SOUNDBITE OF PRESS CONFERENCE)

BRUCE AYLWARD: You know, Wuhan started fast and early. People didn't - we didn't know what we were dealing with. We were learning how to treat this.

AIZENMAN: The more patients they saw, the more medical staff could start identifying what types of care made a difference - which means by the time patients started showing up in hospitals in other provinces, doctors and nurses there had a lot more information about what it takes to keep patients alive. Hospitals in the rest of the world will likely also benefit from that updated knowledge.

(SOUNDBITE OF PRESS CONFERENCE)

AYLWARD: The second thing was just the sheer scale of the numbers.

AIZENMAN: Aylward says hospitals in Wuhan were flooded with thousands of sick people, which stressed their capacity to provide the kind of round-the-clock intensive care a patient needs if they've got a severe or critical case of COVID-19. Elsewhere in China, the caseload was much lower. The implication for other countries - it's worth trying to at least slow the pace of an outbreak so as to keep the number of patients from overwhelming your hospitals.

The final factor...

(SOUNDBITE OF PRESS CONFERENCE)

AYLWARD: At the beginning of this outbreak, remember people were finding severe disease and that's why the alarm bells went off.

AIZENMAN: Those early severe cases made COVID-19 look like a much bigger killer. It was only after officials in China stepped up surveillance that they started uncovering many more mild cases. And that's a pattern we're likely to see in other countries, too. In other words, there's a good chance the fatality rate in nations with good health systems will be lower than what we first saw in China. Still, it's worth noting that even once China got the death rate down to 0.7%, that's still about seven times greater than the death rate for flu. Also, some of the data from China shows that for patients older than 70, the death rate triples.

Anna Yeung-Cheung is a microbiologist at Manhattanville College in New York. She even worries about health workers.

ANNA YEUNG-CHEUNG: For a health care worker, you would say, OK, they're young.

AIZENMAN: But Yeung-Cheung, who's originally from Hong Kong, notes that a lot of doctors there died during the SARS coronavirus outbreak of 2002-2003. And hundreds of Chinese health workers came down with COVID-19, possibly, at least in part, because they were working so hard.

YEUNG-CHEUNG: We need to take into account the stress that they're undergoing. This is stress to their body.

AIZENMAN: One more reason for other countries to do what they can to keep this disease contained.

Nurith Aizenman, NPR News. Transcript provided by NPR, Copyright NPR.