The measures were initially designed to help rally international support – financial, operational and medical – for affected regions and to ensure better transparency, but come with the expressed caveat that they should not be used as a reason to economically stigmatise a nation.

Previous PHEIC declarations have been reserved for epidemics in middle-to-low income countries such as the Democratic Republic of Congo, Guinea and Uganda for two separate Ebola outbreaks, Brazil and other Latin American countries with the Zika virus, the return of polio to places like war-torn Syria and Afghanistan, and a global swine flu pandemic in 2009 that started in Mexico.

Antoine Flahault, director of the Institute of Global Health in Geneva, said that given the evolution of the virus, it will only be a matter of time before the alert is sounded.

“Since human-to-human transmission is now established outside China, as soon as it is considered as sustained transmission chains, the WHO will declare a PHEIC,” Flahault said. “As with all UN organisations, there are political games. Of course the bigger the player, the more intense and powerful the pressure.”

The WHO committee that votes on whether to issue a PHEIC was split down the middle on the decision at an emergency meeting last week, and is still on the fence regarding whether to go ahead, with Flahault adding that this is symbolic of the uncharted territory the organisation finds itself it.

The WHO is set to convene again on Thursday to take a new vote on whether the coronavirus constitutes a global emergency, and given the spike in new cases over recent days, it is a decision that will be analysed closely around the world.

“China surely did not want to be called a public health emergency without controlling it themselves,” said Michael Osterholm, an expert in infectious disease epidemiology at the University of Minnesota. “The declaration is not so much about functionality and providing financial support to China, but to let the world know that this is really something that you must not take lightly.”

The WHO was criticised for not acting quickly enough to declare a PHEIC in Ebola-wracked West Africa in 2014, for fear that it would damage the economies of affected countries, including Guinea. In an interview with Associated Press in 2015, the head of pandemic and epidemic diseases at the WHO, Sylvie Briand, defended the action.

“What I’ve seen in general is that for developing countries it’s sort of a death warrant you’re signing,” Briand said at the time, referring to the economic impact.

Furthermore, given the fact that there is no official framework on how other nations should respond to a public health emergency, it is unclear what additional economic damage would be inflicted upon China, given that the rapid spread of the virus has already captured headlines around the world.

“From an economic and financial perspective, what ultimately matters is how quickly the further spread of infection is stemmed – whether an emergency is declared or not – and efforts to stem the coronavirus infection are indeed very much in motion currently,” said Atsi Sheth, chief credit officer at Moody’s Investor Services.

But economic damage to both China and international corporations is mounting rapidly. On Wednesday, British Airways and Lufthansa announced they were suspending all flights in and out of China, while a number of other airlines have scaled back their services to China.

Starbucks also announced that it would close about half of its more than 4,000 stores in China. Car manufacturers, including Toyota and Hyundai, have delayed re-opening their factories after the Lunar New Year holiday, and Apple issued cautionary advice on the impact of the outbreak on its production, much of which is located in China.

Many plants around the country are expected to remain closed amid a series of travel bans that left migrant workers stranded in their hometowns. Stock markets also remained shut, with the Lunar New Year holiday being compulsorily extended into next week by the State Council.

“There is just so much uncertainty and everyone is thinking about the worst case scenario, such as what if it spreads more, what if the mortality rate jumps, what if I get stuck here? And that causes panic which is really damaging to the economy,” said Imogen Page-Jarrett, an analyst covering China and health care at the Economist Intelligence Unit in Beijing.

She added that other nations were not waiting for the WHO’s signal to start enforcing sterner checks at borders and setting up quarantines for new arrivals that had spent time in Wuhan.

“If a global health emergency was declared, then we would see more forceful reactions from other countries,” Page-Jarrett said. “But I think even in the absence of that declaration, we saw Hong Kong on Tuesday cutting the high speed rail and slashing flights from China.”

Mark Humphrey-Jenner, a finance professor at the University of South Wales, said that the material impact of a global emergency alert would be minimal, but the more subtle impact would be what it represents.

“It does not change anything per se, but it would likely mean there’s an increase in mortality and would represent a shift in attitude, signalling that the level of emergency indicated is quite severe,” he said.

US Federal Reserve chairman Jerome Powell, during a press conference in Washington on Wednesday after keeping its key interest rate unchanged in a low range of 1.5 per cent to 1.75 per cent, issued a cautionary note in the wake of the virus.

“There is likely to be some disruption to activity in China and globally,” Powell said. “It’s very uncertain how far it will spread and what the [economic] effects will be in China, for its trading partners, and around the world.... We are very carefully monitoring the situation.”

In the case of a WHO global health alert, there would be no obligation on countries to impose further travel restrictions on China. Indeed, such measures have been rarely used in the past.

After the 2009 swine fever pandemic originated in Mexico, individual carriers including United Airlines in the US and Thomas Cook in Britain reduced Mexican flights, but only a handful of nations including Argentina, Cuba and Ecuador banned all air traffic.

Indeed, while stories emerged earlier this week that the White House was preparing airlines to start cancelling flights – swiftly denied by the Trump administration – in previous PHEIC situations, the US has issued no such doctrine.

In 2014, then US president Barack Obama was criticised by his own Democratic Party for not banning flights from Ebola-hit West Africa, while a host of developing countries, ranging from Kenya, to North Korea, to Suriname, did ban flights.

The lack of an official response framework post-PHEIC creates “huge challenges” – particularly when it involves the geopolitical clout of China, said viral disease expert Osterholm, whose work included combating the spread of severe acute respiratory syndrome (Sars), swine flu and Zika within the US. Developing countries may be willing to ban visitors from, say, Guinea, but will be more reluctant to fall foul of Beijing.

“In 2009 when [swine flu] first emerged on April 26 2009 I was on conference calls about whether should we close the border with Mexico to stop the movement of the flu virus,” Osterholm added. “I was one of those who argued it's way too late – it’s already done. And one month later, May 27, the WHO released a report showing that 47 countries had already confirmed the virus in their country.”

Additional reporting by Associated Press