President Donald Trump was finally persuaded to take the threat of the novel coronavirus seriously after watching the Fox News host Tucker Carlson talking about it on his show last week, The Washington Post reported.

Without mentioning the president by name, Carlson criticized those downplaying the virus and comparing it to the common flu.

Carlson called the outbreak a "major event," stressing, "It's definitely not just the flu."

Trump has since dramatically shifted his tone on the illness, taking part in daily White House briefings about the illness and announcing new measures meant to halt the progress of the outbreak.

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President Donald Trump began to take the novel coronavirus seriously only after seeing the Fox News host Tucker Carlson talking about it on his show last week, two White House sources told The Washington Post.

Trump had been downplaying the threat of the virus for weeks, including in a tweet as recent as March 9 comparing the disease to the common flu.

But a monologue in which Carlson bluntly declared "this is real" is said to have changed Trump's mind.

Carlson — a staunch supporter of Trump who has advised him in an informal capacity — also offered a thinly veiled critique of the president and those like him who'd sought to downplay the impact of the disease COVID-19.

"People you trust — people you probably voted for — have spent weeks minimizing what is clearly a very serious problem," Carlson said.

"It's just partisan politics, they say. Calm down. In the end, this is just like the flu, and people die from that every year. Coronavirus will pass, and when it does we will feel foolish for worrying about it."

He added: "Maybe they're just not paying attention, or maybe they believe they're serving some higher cause by shading reality ... And there's an election coming up. Best not to say anything that might help the other side. We get it. But they're wrong."

Carlson called the outbreak a "major event," stressing, "It's definitely not just the flu."

Commenting on the 500 cases that had at that point been recorded in the US, he said: "The real number is without question far higher than that — soon we will have a better sense of just how much higher.

"By then, this epidemic will have caused economic damage whose effects may dog us for years. People you know will get sick — some may die. This is real."

In a statement to Business Insider, White House spokesman Judd Deere rejected the claim that Carlson had prompted Trump to reevaluate his attitude to the illness, directing Business Insider to a list of measures the White House has taken in response to the outbreak, including imposing a ban on some visitors from China back in January.

"The President took decisive action early on to close our borders to the source of the virus and it is because of his leadership and relationships that he has brought together government and private industry for unprecedented collaboration to curb the spread of the virus, expand testing capacities, and expedite vaccine development," said Deere.

Carlson's stark warning contrasted with the approach taken by other Fox News personalities, some of whom spent weeks claiming the disease was being exaggerated by Democrats and the larger news media as part of a plot to damage Trump's presidency.

An NBC News/Wall Street Journal poll taken March 11-13 found a stark divide between Republicans and Democrats on the likely impact of the disease and the measures they were taking to help stop its spread.

According to the survey, 80% of Democrats believed that the worst was yet to come, a point on which scientists agree. Only 40% of Republicans believed the same, the poll found.

The situation changed quickly last week, however, even as that survey was being conducted. Trump declared the coronavirus a national emergency on Friday and this week has taken part in daily White House briefings. On Tuesday, he claimed he had always believed the virus would become a pandemic.