Editor’s note: PolitiFact, which is owned by the Poynter Institute, is fact-checking misinformation about the coronavirus. This article is republished with permission, and originally appeared here.

If your time is short

• Reputable scientists warned early in the outbreak that there was not a totally accurate picture of how deadly the coronavirus was. There’s still not.
• It’s misleading to compare, as Carlson did, the early reported case fatality rates, which reflect deaths among confirmed COVID-19 patients, with more recent infection fatality rates that estimate the death rate for all infected people.
• COVID-19 still appears more lethal than the seasonal flu, experts said. Infection fatality rates that may seem small can lead to mounting death tolls.

See the sources for this fact-check

Tucker Carlson: “The virus just isn’t nearly as deadly as we thought it was.”

Fox News host Tucker Carlson railed against continued statewide shutdowns meant to slow the spread of the coronavirus, claiming in a recent TV segment that they did little to flatten the curve and that “the virus just isn’t nearly as deadly as we thought it was.”

Citing recent studies from hotspots such as New York, Carlson said the virus is “a full order of magnitude less deadly” than public health officials warned.

“The virus just isn’t nearly as deadly as we thought it was, all of us, including on this show,” he said. “Everybody thought it was, but it turned out not to be.”

More than 65,000 Americans have died from COVID-19, the disease caused by the coronavirus, according to the Centers for Disease Control and Prevention. That’s in spite of widespread mitigation efforts to reduce the spread. So how deadly is it?

Estimating the lethality of COVID-19 has been a key question for epidemiologists. In the middle of a pandemic, moving targets make the death rate difficult to pin down.

But experts told us Carlson’s statement is off-track. Many early mortality estimates were based on official counts of confirmed cases, but epidemiologists were consistent in saying those raw numbers didn’t reflect the virus’s deadliness with complete precision.

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The numbers can be confusing

Ideally, epidemiologists could divide the number of deaths by the number of infections to calculate what’s known as the “infection fatality rate.” But there’s no way to get a complete count of the number of infected individuals, largely because so many mild cases go unreported.

Jeffrey Shaman, an epidemiologist at Columbia University, said there could be as many as 12.5 COVID-19 infections for every confirmed case in the U.S.

Still, scientists work with the data they have, even if it’s evolving and varies with patient demographics and location. Some of the first widely reported death rates were what are called “case fatality rates,” which are calculated by dividing the number of known deaths by the number of reported cases.

On March 3, for example, the World Health Organization announced that 3.4% of confirmed coronavirus patients around the world had died — a case fatality rate.

Experts told us at the time that the 3.4% was only a snapshot, and one that likely undercounted people with mild symptoms. A WHO spokesperson said it would “change over time.”

The global case fatality rate has actually risen since then. As of May 3, the WHO had tallied 3,349,786 confirmed cases worldwide and 238,628 deaths, for a case fatality rate of about 7%.

Now, tests for antibodies in the blood of people exposed to the coronavirus are offering the first glimpses at what the infection fatality rate could be in states such as New York and California.

The tests haven’t all been as accurate as many experts would like, and the studies of them haven’t all been peer-reviewed. “It remains very clear that we do not know the precise mortality of COVID-19 infection,” said the University of North Carolina at Chapel Hill’s Myron Cohen.

But their preliminary results suggested the infection fatality rate may be below 1%, handing fodder to some who say the COVID-19 threat is overblown.

Carlson said the new information shows COVID-19 is less deadly than expected.

On his show, he cited widely disputed findings from two California doctors. A Fox News spokesperson also pointed to a White House press conference, a JP Morgan chart, and recent antibody studies in California and New York to support it.

But Shaman, the epidemiologist, said Carlson was “cherry-picking evidence.”

Many early figures were case fatality rates, while the estimates reported as a result of recent antibody studies are infection fatality rates. They shouldn’t be conflated, Shaman said.

Seemingly small infection fatality rates can also cause mounting deaths. The New York study showed the state’s infection fatality rate to be around 0.5%, Gov. Andrew Cuomo said.

That matches estimates from a model Shaman constructed, which he said put the U.S. infection fatality rate at 0.56%. But in a worst-case scenario where 70% of Americans are infected, a 0.5% rate could amount to 1.2 million U.S. deaths, Shaman said.

And as we’ve reported, the death toll may be higher than we know.

The infection fatality rate for the flu, which kills thousands of Americans annually, hovers under 0.1% and is calculated annually using a mathematical model that estimates the disease burden.

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Carlson’s sources aren’t foolproof

There are other problems with Carlson’s sources, including the clip he played of one of two California physicians who gained national attention for calling to end the shutdowns.

The doctors, who own an urgent care clinic, used the infection rate among patients tested at their clinic to extrapolate to the entire state and put the death rate at a tiny 0.03%.

The University of Washington’s Carl Bergstrom wrote on Twitter that this amounts to “sampling bias” because patients at an urgent care clinic likely think they’re sick. The doctors’ calculations are like “estimating the average height of Americans from the players on an NBA court,” he said.

Using that 12% infected figure, and a known 1400 deaths in California, they assume 1400 out of 4.7 million have died. That gives them an infection fatality rate of 0.03%. That is, they think that if 10,000 are infected, 3 will die on average.

— Carl T. Bergstrom (@CT_Bergstrom) April 26, 2020

The video was “emphatically condemn(ed)” by the American College of Emergency Physicians and the American Academy of Emergency Medicine; it was also removed from YouTube.

Another report cited by the Fox News spokesperson, from the University of Southern California, followed a controversial study from Stanford University.

A number of experts have since warned that both studies used antibody tests known to yield false positive results. (A USC spokesperson said results were adjusted to account for that.)

Many epidemiologists said the infection fatality rate would be lower

Carlson’s claim that COVID-19 was projected to be deadlier for infected patients also discounts what many experts said months ago.

“No one knowledgeable thought it was as deadly as known deaths divided by known cases,” said Marc Lipsitch, professor of epidemiology at the Harvard T.H. Chan School of Public Health.

“Every responsible epidemiologist has been saying that the number of cases is certainly more than those we know about, especially in the U.S., where testing has been inadequate.”

Many experts, including Dr. Anthony Fauci, the nation’s top infectious disease expert, said preliminary case fatality rates could be inflated. The WHO said early on, including in mid- February, that the infection fatality rate would be lower than the initial case fatality rates.

The Imperial College of London, which projected in March that the U.S. could see 2.2 million deaths if it had no response, estimated that 0.9% of infected COVID-19 patients would die.

“It is surprisingly mild only to those who were not listening to competent epidemiologists, and it is in fact considerably worse than seasonal flu,” Lipsitch said.

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Our ruling

Carlson said the coronavirus “just isn’t nearly as deadly as we thought it was.”

Scientists warned early in the outbreak that the raw number of confirmed cases didn’t give a fully accurate picture of mortality.

It’s misleading for Carlson to compare early case fatality rates — which divide the number of known deaths by the number of confirmed cases — with newer estimates of the infection fatality rate. The infection fatality rate should be lower, as experts have said for months.

It’s premature to say as a matter of fact that a far rosier picture has emerged.

We rate this statement Mostly False.