“In many cases China is the sole source of that material,” Gottlieb, who led the FDA for two years under Trump, said during a hearing on Capitol Hill.

At a time when China would be focusing its production on domestic demand rather than international export, and amid wide scale disruption to industry across the country caused by the coronavirus outbreak, Gottlieb said the contagion had exposed “a critical choke point in the supply chain for pharmaceuticals”.

Biomedical researchers around the world are scrambling to find an effective treatment and develop a vaccine for the disease, named Covid-19 on Tuesday by the World Health Organisation (WHO).

The contagion has killed more than 1,300 people and infected over 60,000, the vast majority in China.

Beyond pharmaceuticals, vulnerabilities in the supply chain could also affect the flow of health care provisions like gloves, masks and materials used in patient isolation, said Julie Gerberding, former head of the US Centres for Disease Control and Prevention (CDC).

Luciana Borio, who led medical and biodefence preparedness in Trump’s National Security Council (NSC) until 2019, said the US had failed to protect the supply of essential medicine and medical equipment. “That needs to change going forward,” she said.

The former officials were testifying before the Senate homeland security and governmental affairs committee, the upper chamber’s chief oversight body.

As was the case at a House of Representatives hearing about the coronavirus outbreak last week, administration officials declined to testify before the panel, disappointing committee members of both parties.

Officials were occupied with a closed-door briefing of lawmakers on Wednesday morning, said Senator Ron Johnson, a Republican from Wisconsin and the committee chairman. “But I think it’s extremely important the public understands these things as well,” he added.

The hearing came as lawmakers were grappling with the Trump administration budget plan that proposes sweeping cuts to areas including health, scientific research and the environment.

Coronavirus ‘could cut China’s purchases of US goods’ under trade deal

Released on Monday, the budget proposes more than US$570 million in cuts to the CDC – equivalent to a year-on-year reduction of just over 9 per cent.

Among the cuts would be US$85.3 million from funding for emerging and zoonotic (animal-to-human) infectious diseases, US$57.5 million slashed from public health scientific services – including surveillance and epidemiology – and a US$25.2 million reduction in public health preparedness and response.

Administration officials have highlighted the emergency financing available to the CDC via its infectious disease rapid response fund, which would gain an additional US$50 million under the proposed budget. But on Wednesday, the former officials amplified repeated calls for a more farsighted approach to fortifying the country’s defences.

The CDC has suffered from “herky-jerky funding”, said Gerberding, who led the agency from 2002-09 during the George W. Bush administration.

“When something happens, as a nation we’re very competent at making an emergency investment and stepping up in the crisis to get miraculous things accomplished,” she said. “But we don’t sustain it.”

Health experts tell US Congress travel bans won’t stop coronavirus

As well as cuts to the CDC, Trump’s budget calls for slashing US$3 billion from the National Institutes for Health (NIH), the government’s research body that is spearheading the development of a coronavirus vaccine. The cuts would include a US$1.76 billion reduction in money for NIH-issued research grants.

At Wednesday’s hearing, Senator Kamala Harris, Democrat of California, called the budget “one in a long line of attacks on our country’s public health system that we’ve seen over the past three years”.

The fiscal budget is a largely symbolic articulation of the administration’s priorities for the year to come, and is certain to be rejected by the legislative branch, which oversees spending.

Criticising the administration’s proposal to slash CDC funding, House Speaker Nancy Pelosi asked on Tuesday: “What could he be thinking? Maybe I’m using that term loosely.”

Coronavirus: ‘people may succumb’, says Singapore as cases hit 50

Citing those same cuts during a grilling of the White House’s acting budget director on Capitol Hill on Wednesday, Representative Rosa DeLauro, Democrat of Connecticut, called the budget “nothing but an Orwellian distortion of what the reality is”.

Amid the coronavirus outbreak, the Trump White House has again been denounced for disbanding the NSC’s epidemic preparedness directorate in 2018.

Senator Chris Murphy, Democrat of Connecticut, last week urged the administration to reinstate the directorate “before this turns into a full-blown crisis”, calling the temporary task force handling the White House response to the coronavirus “simply insufficient”.

For his part, Trump has remained publicly upbeat about both the efficacy of China’s response to the outbreak and the US’ ability to safeguard Americans from it. On Tuesday he suggested that the warmer weather of spring would make the virus “go away”.

But speaking on Wednesday, former FDA chief Gottlieb questioned such a conclusion, pointing to the number of cases in Singapore, where high temperatures are reaching 32 degrees Centigrade (89.6 Fahrenheit).

With some 50 confirmed infections, the city state is the worst-hit region outside China, second only to the 203 cases on a cruise ship under quarantine in Japan.