Efforts to ensure that any Covid-19 vaccine is available equitably across the globe are faltering after the United States refused to take part in a World Health Organisation (WHO)-backed initiative.
The US, in the past a major backer of global efforts of this type, said on Tuesday it will not work with the international cooperative effort led by the WHO, the Coalition for Epidemic Preparedness Innovations (CEPI), and Gavi, the Vaccine Alliance.
The effort - known as the Covid-19 Vaccines Global Access Facility, or Covax - is a pooled procurement scheme aimed at developing and distributing Covid-19 vaccines. In particular, it wants to secure 2 billion doses of any successful vaccine for the world's most vulnerable people by the end of 2021.
The idea is that it will use funding from richer countries to do so via a separate facility that is part of the scheme, but richer countries can also use it to get doses for their own populations.
However, countries including the United States, Japan and the United Kingdom are already negotiating directly with vaccine developers (in some cases alongside signing up for the scheme) to ensure their citizens are first in the queue - so-called "vaccine nationalism" - which could mean poorer countries miss out.
In fact, according to the latest count by news agency AFP, a handful of developed countries have put in orders for at least 3.1 billion doses of various different vaccine contenders - and that's before tests on them have even finished.
Unsurprisingly, President Trump has led the way in this field: the US has signed contracts guaranteeing at least 800 million doses from six manufacturers for a population of 330 million. That is more than twice as many doses as needed per head, if all of the vaccines end up working - and that's a big if: no vaccine has yet passed all the hurdles required, and only around 15-20 per cent of vaccines in development usually make it.
On Tuesday, White House spokesman Judd Deere said that the US would continue to go it alone, and would not be "constrained by multilateral organizations influenced by the corrupt World Health Organization and China".
Reacting to the US decision, head of CEPI, Dr Richard Hatchett, said he was "concerned".
"What we need to persuade global leaders is that as a vaccine becomes available in these initially limited quantities, it needs to be shared globally, that it shouldn't be the case that just a handful of countries get all of the vaccine that is available in the first half of 2021," he said.
He wants at all costs to avoid the scenario of 2009, when rich countries managed to bag the first vaccines of the H1N1 flu.
"I am concerned about it," he added.
The Trump administration's reluctance to get involved follows its decision to withdraw from the WHO in July.
However, it isn't the only potential backer with concerns over the Covax scheme: earlier this year the European Commission said it was too slow and expensive, and set up its own vaccine procurement process for its 27 member states.
But in a U-turn this week, the EU said its members may now use Covax alongside its own scheme, and pledged €400m to provide support for poorer countries.
Around 170 other countries are already signed up to Covax: 80 higher-income countries, which will use it to procure doses and may also pledge funding to support lower-income economies, and 72 lower-income countries, which will be able to access vaccines through it. That represents around 70 per cent of the world's population.
A Gavi spokesperson said: "Covax is the only truly global solution to end the acute stage of Covid-19 pandemic and the only way we can ensure that doses of Covid-19 vaccines don’t get cornered by a small number of countries."
The scheme's leaders have stressed that the support element is critical.
"Only together can we beat Covid-19 and save lives," the WHO's Director General, Dr Tedros Adhanom Ghebreyesus, has said.
However, there are significant financial hurdles remaining. Last week, Cepi, Gavi and the WHO said governments, vaccine manufacturers, organisations and individuals had committed $1.4bn to vaccine research and development so far, but an additional $1bn was urgently needed to move the portfolio of potential vaccine candidates forward.
Furthermore, a financing instrument launched by Gavi in June - the key element that is aimed at ensuring lower and middle income countries can participate in Covax - has only raised $700m of $2bn needed so far.
There have been some wins, though: a collaboration between Gavi, the Bill and Melinda Gates Foundation and the Serum Institute of India will ensure up to 100 million doses are available to low and middle income economies, through Covax, at $3 a dose, with more available if needed.
A separate agreement with the drug manufacturer AstraZeneca guarantees a further 300 million doses to be distributed through Covax - all of which only apply if the vaccines in development actually work.
Countries now have until 18 September to make commitments to the Covax scheme.
The motivation should be clear: experts have repeatedly stressed not only the moral imperative of ensuring that the world's most vulnerable populations have access to a vaccine, but also the "enlightened self-interest" of doing so. If the virus remains active somewhere, they say, it effectively remains everywhere, thanks to our globalised world.
Alex Harris, Wellcome’s Head of Global Policy, said: “It is disappointing that the US has decided not to join Covax. The only way we’re going to end this pandemic is if countries work together.
“Vaccinating high-risk people in every country first is the fastest and most effective exit strategy."
But there's another issue as well, which public health experts in the US were quick to leap on.
Nine potential vaccine candidates currently being supported by Cepi are part of the Covax initiative, seven of which are in clinical trials - including the Oxford University/Astra Zeneca vaccine, alongside the German and US candidates, seen as the leading bids so far.
The Covax organisers are also in talks with nine more developers and open to further discussions. That means it is a much broader vaccine portfolio than any one country alone could commit to - even the US.
Perhaps that's why leading public health expert Dr Eric Feigl-Ding, an epidemiologist at Harvard University, greeted the news of the US decision with one word: "Terrible."
As well as the global impact, he added on Twitter that the policy amounted to "shooting ourselves in the foot... It puts all our eggs in a limited basket of US-funded vaccines. But there's dozens more part of the Covax-consortium we could have access to if we joined."
It effectively means the US has doubled down on its bet that the vaccine candidates it has already backed will work. If they don't, without being part of Covax, America may not have access to the others - and that could risk not just global lives, but American lives.
That's an argument that the "America First" administration of Mr Trump may well find more convincing than the others.
Or as Dr Feigl-Ding put it: "Turning down an insurance policy during a pandemic is nonsensical and madness."
Protect yourself and your family by learning about Global Health Security