Capital outflows from China have begun to accelerate and the first concrete trade data from Asia have exposed a drastic disruption of supply chains, raising the risk of a broader global financial shock unless the coronavirus is brought under control within days.

Analysts are already downgrading growth forecasts sharply as the de facto lockdown of Chinese cities engulfs most of its core economy, extending as far as Guangzhou, Tianjin, Ningbo and the crucial industrial hubs of the greater Shanghai region. Almost 400 million people are now under some from of coercive quarantine.

“We’re expecting a serious contraction in the first quarter. It looks like quite nasty numbers,” said Freya Beamish from Pantheon Macroeconomics. The group’s base case is that true GDP - as opposed to the ‘smoothed’ official figures - will fall to minus 1pc.

Even this grim outcome assumes that the 2019-nCoV virus is sufficiently contained to allow key manufacturing and components plants to reopen next week.

Pantheon said the damage could be as bad as minus 2.5pc if the paralysis drags on into March. A Chinese growth shock of this magnitude would push much of the world economy towards the recessionary danger zone. Relative US strength is a double-edged sword since it also lifts the dollar and tightens financial conditions in offshore funding markets.

Standard & Poor’s says China accounts for a third of global growth and is effectively the arbiter of the international cycle through four key channels: commodities, capital goods, integrated supply chains, and tourism.

There is an even bigger worry, that the epidemic could set off a wave of defaults among smaller businesses and overstretched Chinese construction companies, many of them with large bond liabilities in US dollars and on maturities of less than 12 months. Lu Zhengwei from Shanghai’s Industrial Bank says smaller firms will hit the wall within a month if the shutdown continues.