WASHINGTON (BLOOMBERG, REUTERS) -In the race to develop a vaccine to end the Covid-19 pandemic, governments, charities and Big Pharma firms are sinking billions of dollars into bets with extraordinarily low odds of success.

Historically, just 6 per cent of vaccine candidates end up making it to market, often after a years-long process that doesn't draw big investments until testing shows a product is likely to work.

But the traditional rules of drug and vaccine development are being tossed aside in the face of a virus that has infected 5.2 million people, killed more than 334,600 and devastated the global economy.

With Covid-19, the goal is to have a vaccine identified, tested and available on a scale of hundreds of millions of doses in just 12 to 18 months.

Drug companies and the governments and investors that finance them are boosting their "at-risk" spending in unprecedented ways. The overriding consensus among drug company executives, government health officials and pandemic-response experts is that the risks are necessary to ensure not only that a vaccine for the new coronavirus is developed quickly, but that it is also ready to distribute as soon as it's approved.

"The crisis in the world is so big that each of us will have to take maximum risk now to put this disease to a stop," said Dr Paul Stoffels, chief scientific officer at Johnson & Johnson, which has partnered with the US government on a US$1 billion (S$1.42 billion) investment to speed development and production of its still-unproven vaccine.

"If it fails," Dr Stoffels said, "it will be bad."

The scale of the coronavirus vaccine race has no historical parallels. The Coalition for Epidemic Preparedness Innovations (CEPI) - a vaccine-development consortium supported by private donors as well as the United Kingdom, Canada, Belgium, Norway, Switzerland, Germany and the Netherlands - has identified at least 115 ongoing vaccine initiatives worldwide.

The race is shattering norms of speed and safety in drug and vaccine development. Some developers are running safety and efficacy trials in tandem, instead of sequentially, as is typical, and short-cutting traditional testing protocols. Others are working with regulators in multiple countries simultaneously, looking for the quickest path to market.

Many of the candidates attracting the most investment rely on proven vaccine approaches being adapted by Big Pharma companies with regulatory and production acumen. Some funders are gambling on smaller biotech companies and academic labs, which may have promising technologies but little to no experience getting a drug or vaccine approved and produced at scale.

Many governments are pouring money into vaccine initiatives with expectations that they will be first in line if a viable vaccine emerges.

Arcturus Therapeutics Holdings Inc, a San Diego biotech, is receiving up to US$10 million from the Singapore government to develop its mRNA-based coronavirus vaccine candidate in partnership with the Duke-National University of Singapore Medical School.

If the vaccine is approved, Singapore gets first access, said Arcturus CEO Joseph Payne. Everything after that, he said, goes to "whoever pays for it".

"Arcturus is not responsible for the ethics of distribution - governments are - but in order for governments to get the vaccine, they need to pay for it," Payne said. "The country that will win is the country that stockpiles multiple vaccines at risk."

In China, a major global producer of vaccines, the government is backing several coronavirus vaccine projects, raising the prospect it will inoculate its 1.4 billion people first. President Xi Jinping of China has said any successful vaccine developed there will be made available as a global public good.

One government-backed effort, by Sinovac Biotech Ltd, is already testing vaccine candidates in humans and awaiting initial data.

Sinovac got 60 million yuan (S$11.97 million) in low-rate credit lines through a discount loan programme supported by China's central bank.

Government officials quickly made land available for the company to build production plants, including a factory meant to produce up to 100 million doses a year of its coronavirus vaccine.

Sinovac would not discuss how much public money is being invested. The relevant government agencies declined requests for comment.

On April 24, the World Health Organisation announced a "landmark collaboration" across the international community to raise US$8 billion to accelerate coronavirus vaccine development and ensure equitable access worldwide to any successful vaccine.

Countries across Europe, Asia, Africa, the Middle East and the Americas announced their participation, but the United States and China did not.

"There will be no US official participation," a spokesman for the US mission in Geneva said, adding that the US supports "global cooperation to develop a vaccine".

The US on Thursday threw its weight behind one of the fastest-moving experimental solutions to the coronavirus pandemic, pledging as much as US$1.2 billion to AstraZeneca Plc to help make the University of Oxford's Covid vaccine.

The UK drug maker received the money from the US Biomedical Advanced Research and Development Authority (BARDA) and said it has secured capacity to make one billion doses.

BARDA, the US R&D agency, is one of the biggest vaccine funders, with some US$5 billion to spend. The agency plans to invest in five vaccine candidates, focusing mostly on projects from experienced drug makers.

"Each is coming with a lot of prior experience," said Mr Rick Bright, who until this month was BARDA's director. "They all know how to scale up."

The US has also backed projects underway at Moderna Inc and France's Sanofi, fuelling concerns that other parts of the world could fall behind.

AstraZeneca Chief Executive Officer Pascal Soriot said in an interview with Bloomberg Television the drug would enter phase III clinical trials in June, and they'll run to the end of August.

The US agency has also provided US$30 million for Sanofi's Covid vaccine candidate and US$226 million for its work to counter pandemic influenza. A coronavirus shot developed by the French company would probably go to Americans first, Chief Executive Officer Paul Hudson said last week in an interview with Bloomberg News.

Sanofi said later that it would make the vaccine available everywhere.

While the absence of a European counterpart to BARDA has slowed efforts to secure supplies, Mr Hudson said the French company is in talks with several governments on possible arrangements.

Having reserves ready worldwide to immediately inoculate critical populations - healthcare workers, the elderly, people made vulnerable by medical conditions - would stamp out the pandemic faster and reignite economies, said Dr Richard Hatchett, a physician who managed US pandemic flu policy under former President George W. Bush and returned to advise the Obama White House during the 2009 swine flu pandemic.

The alternative, said Dr Hatchett, who now heads the Coalition for Epidemic Preparedness Innovations (CEPI), is a replay of past pandemics, including the H1N1 influenza outbreak of 2009, with wealthy countries hoarding the vaccines.

If that happens, pandemic experts warn, infection hot spots will continue to pop up, each with the potential to create a new wave of illness.

Although it's helpful that countries like the US are stepping up and contributing to vaccine development, the only way to move on from the pandemic is to ensure equal access to a jab, said Dr David Heymann, a professor of infectious disease epidemiology at the London School of Hygiene & Tropical Medicine.

It's "important that all countries have equal risks and, at the same time, equal response mechanisms so that travel and trade can begin, and that can only be accomplished if everyone has the same level of protection", Dr Heymann said.