Three weeks ago there was much talk of a Chernobyl moment for China's Communist Party, discredited by totalitarian attempts to suppress news of the spreading coronavirus in Wuhan.

But fast-moving events can play wicked tricks, especially on a White House allergic to scientific facts. Covid-19 is more likely to be the Chernobyl moment for Donald Trump.

His systematic destruction of US pandemic defences - policy vandalism of the first order - and surreal efforts to conjure away the virus with denialist spin brings an unthinkable prospect into play.

The coming backlash may sweep Bernie Sanders into power on a socialist manifesto of Piketty wealth taxes, the partial closure of the US oil and gas industry, and vast increases in the size and role of the US government, all with an implicit budget deficit of $3trn. Try feeding that into your models for GDP growth, equity prices or bond yields.

The Trump administration has cut funding for the US Centre for Disease Control (CDC) by 9pc. This month he proposed slashing it a further 16pc. The worst hit area has been pandemic preparation. The CDC's global health security initiative has been chopped by 80pc, reducing country coverage from 49 to 10.

Mr Trump got rid of the US Complex Crises Fund. He shut down the pandemic and global health machinery at the White House, and fired the lot. He tried to cut the budget of the National Institutes of Health - the world's finest concentration of science - by 20pc in 2018 and 27pc in 2019. Congress stopped the worst but damage has been done.

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Tom Frieden, ex-head of the CDC, warned two years ago the cuts would leave the US at the mercy of the next killer virus. "The surveillance systems will die, so we won't know if something happens. You can't pull up the drawbridge and expect viruses not to travel," he said. Ouch.

It has been a war on science. Mr Trump's cuts have nothing to do with fiscal austerity. They happened just as he was pushing through tax cuts. The science cuts were ideological.

And now the White House has a disaster on its hands. "The epidemiological conditions for a pandemic are met," said Prof Marc Lipsitch, Harvard's guru on infectious diseases. Don't be fooled by the seemingly low numbers of infections in the US (57 as I write): the country has tested just 426 people. Only three of the 100 public health labs even have working test kits.

One reason why South Korea appears to have so many cases is because it has carried out 44,981 tests. "They are looking, so they are finding," says professor Caitlin Rivers from Johns Hopkins University.

Dr Nancy Messonnier, head of the CDC, is doing her best. She told America on Tuesday that Covid-19 cannot be stopped and public policy will have to switch from containment to mitigation (already Japan's policy) - a way of saying the virus will ultimately circulate like flu.

"It's not so much of a question of if this will happen in this country any more but a question of when this will happen. We are asking the American public to prepare. This might be bad," she said.

The White House will have none of this. The virus is "very much under control" and a vaccine is very close, tweeted Mr Trump.

Up to a point. Key indexes on Wall Street and global bourses have this week fallen through the first key lines of technical support. Masanari Takada from Nomura says global macro hedge funds have changed strategies almost overnight since Covid-19's global break-out, switching to trades that "prepare for a global recession". Larry Kudlow, the White House economics chief, persists bravely. The US containment of the coronavirus has been "pretty close to airtight". Growth in the US will be unscathed.

Has nobody told him US firms with tight supply chains are fast running down their inventories, or the full effect of cancelled container shipping from Chinese and East Asian ports has not yet been felt? Little is returning to normal. China's economy remains closed and there is a critical shortage of workers at ports. Ships cannot even dock.

The Baidu index shows 72pc of migrant workers have not returned to the big cities since the Lunar New Year. Coal use at major power plants is down 47pc. The longer this goes on, the greater the global economic shock, even if you believe the fairy tale that Covid-19 is a local Chinese virus and won't cross oceans.

Undaunted, the Trump camp is putting out the message through talk radio and in cabinet testimony on the Hill that virus chatter is scaremongering by political opponents - a line also adopted by the insouciant leader of Lombardy in Italy.

Yesterday the head of US homeland security, Chad Wolf, told a stunned Senate committee the death rate of Covid-19 is akin to normal winter flu. He doubled-down when pressed by a senator who clearly knew the designated chief of US emergency preparations does not understand the elementary facts of the matter.

The average flu death rate is around 0.1. Tracking data from China shows a 4.0pc mortality rate in Wuhan, 2.8pc in Hubei, and 0.8pc in other regions, but rising. The ratio rockets for the late-middle aged and elderly.

Furthermore, only a small fraction of people contract flu each year because the rest are vaccinated or have acquired immunity. There will be no Covid-19 vaccine for months. Nobody has immunity.

The Trump administration is taking an insane political gamble by pitting itself against the CDC and against the US fraternity of virologists. It will lose this bet. I also suspect that Covid-19 will expose deep failings within the US health-care and insurance system.

Many poor Americans without coverage or Medicaid will try to tough it out at home rather than risk ruinous medical costs. Illegal immigrants will avoid the health surveillance system for fear of being deported.

The disease will spread in these large, distressed pockets before sweeping the leafy suburbs. The only way to slow the internal contagion is to offer free testing and care for anybody with Covid-19, as Singapore is doing in what has become the world's gold standard regime for this crisis.

If the CDC is right and a US epidemic is on its way, the unfolding drama and shocking death rate will work to the advantage of Sanders in the Democratic primaries.

It could conceivably propel the septuagenarian firebrand into the White House with a majority in both houses of Congress. Just wait until the global macro funds sink their teeth into that prospect.

What are the Dow index and the S&P 500 worth in a global economy facing - potentially - the worst 'sudden stop' since August 1914, and a new America led by a President Sanders with a mandate for socialist upheaval? Let's be generous and say about half of current levels.

(© Daily Telegraph, London)