As fear over the spread of coronavirus tightens its grip on the world, US President Donald Trump wants you to know that everything is under control.

"We've had tremendous success, tremendous success beyond what many people would've thought," he told journalists in the White House briefing room.

"We have the greatest experts, really in the world, right here.

"The risk to the American people remains very low."

It was a classic Trump branding exercise.

But if the purpose was to steady the horses — a worthy goal — it didn't work.

It turns out the coronavirus is bigger than Trump.

For just the second time in more than three years Trump felt the matter was urgent enough to warrant addressing the media directly in the West Wing.

Donald Trump appointed his VP Mike Pence to coordinate the US Government's response to the coronavirus outbreak. ( Reuters: Carlos Barria )

But as he uttered those reassuring words and revealed he had put Vice-President Mike Pence in charge of the situation, news was breaking on the other side of the country about the first sign of a possible break-out.

A patient in northern California, who hasn't travelled overseas, nor been in contact with anyone known to have the disease, has tested positive.

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It suggests an infected person has been moving through the community there.

Could this be Trump's next Sharpie-gate?

Everything Trump said appeared to be aimed at down-playing the seriousness of the situation at hand.

"The risk to the American people remains very low," Donald Trump insisted at a press conference on the coronavirus crisis. ( Reuters: Carlos Barria )

"It's a little like the regular flu that we have flu shots for," he said.

"And we'll essentially have a flu shot for this in a fairly quick manner."

And when a journalist pointed out that COVID-19 has a fatality rate of around 2-3 per cent, while the flu is about 0.1 per cent, Trump disagreed.

"The flu is much higher than that," he said.

But the greatest contradiction and confusion came when Trump introduced Anne Schuchat, the principal deputy director of the Centres for Disease Control and Prevention (CDC).

"It's the perfect time for businesses, healthcare systems, universities and schools to look at their pandemic preparedness plans," Dr Schuchat said.

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"Dust them off and make sure they're ready … we do expect more cases."

The words underlined the warning from her colleagues, who described the spread of COVID-19 within the United States as "inevitable" the previous day.

But after heaping praise on the experts flanking him, Trump made it clear he didn't agree with them on this.

"Nothing is inevitable," he stressed.

"There's a chance it could be worse. There's a chance it could get fairly, substantially worse, but nothing is inevitable."

Donald Trump was criticised in September 2019 for holding up a hurricane tracking map which appeared to be doctored. ( Reuters: Jonathan Ernst )

It brought back memories of his very public disagreement with government meteorologists about the likely path of Hurricane Dorian, which became known as Sharpie-gate after someone doctored a predictive map with Trump's preferred felt-pen.

Trump blames Democrats for stock market falls

Coronavirus hasn't had blanket coverage in the US, like it has in Australia.

In the past few weeks, the cable TV news media has been almost entirely focused on the bitter and divisive contest to choose a presidential challenger, which is set to climax on Super Tuesday next week.

But Wall Street's woes have certainly caught Trump's attention.

He's intensely focused on every stock market move, claiming credit for every strong result at the close of the Dow Jones.

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On Monday and Tuesday this week, the Dow Jones fell nearly 2,000 points.

Rather than accept the obvious fact that coronavirus was the driving force, Trump chose to blame his political opponents' messy debate performance.

"I think the financial markets are very upset when they look at the Democrat candidates standing on that stage," he said.

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"When they look at the statements made by the people standing behind those podiums, I think that has a huge effect."

The problem with that logic is that the debate happened on Tuesday night (local time), after the markets closed.

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The day after Trump's press conference pep-talk was another bloodbath for stocks, down almost 1,200 points.

In fact, in the space of a week the Dow Jones has racked up losses of more than 12 per cent.

Trump's record on truth could come back to bite him

At times of crisis, the markets — and everyone else — need clear, credible and reliable information from those in charge.

Contradiction and confusion only add to the fear, and potentially put people in harm's way.

But Trump's record appears to be against him.

The fact he's made 16,241 false or misleading claims since taking office, according to the Washington Post's Fact Checker's database, isn't particularly helpful.

Pence has been put in charge of the response, but reports suggest one of his key responsibilities was managing the message.

China has rightly come under fierce criticism for being loose with the truth about the spread and severity of COVID-19, especially in the early days of the outbreak.

Some even suggested it could become a "Chernobyl moment" for China's President Xi Jinping, in reference to former Soviet Union leader Mikhail Gorbachev's claim that the attempted cover-up of the 1986 nuclear plant disaster ultimately led to the fall of the communist bloc.

In the West Wing briefing room, one reporter asked whether we could "legitimately trust" Xi and the communist regime to be forthcoming and forthright on this issue.

No-one asked the same question about the US President.