U.S. Will Pay $1.6 Billion to Novavax for Coronavirus Vaccine.  The Maryland-based company, which has never brought a product to market before, just made the biggest deal to date with the Trump administration’s Operation Warp Speed.

The U.S. government will pay drugmaker Sanofi and GlaxoSmithKline up to $2.1 billion to develop and deliver 100 million doses of their potential coronavirus vaccine, the companies announced Friday.

More than half of the $1.5 billion will be used to support further development of the vaccine, including clinical trials. The rest will be for manufacturing and delivery of the 100 million doses, the companies said. The U.S. will have the option to order an additional 500 million doses, they said.

Credit…Andrew Caballero-Reynolds/Agence France-Presse — Getty Images

The federal government will pay the vaccine maker Novavax $1.6 billion to expedite the development of a coronavirus vaccine. It’s the largest deal to date from Operation Warp Speed, the sprawling federal effort to make coronavirus vaccines and treatments available to the American public as quickly as possible.

The deal would pay for Novavax to produce 100 million doses of its new vaccine by the beginning of next year — if the vaccine is shown to be effective in clinical trials. That’s a significant bet on Novavax, a Maryland company that has never brought a product to market.

With this deal, the federal government has now invested nearly $4 billion in companies pursuing vaccines, but has provided little information about how Operation Warp Speed is spending money, which agencies the funding is coming from or how decisions are being made.

That money has gone to six companies with varying track records and, in many cases, promising but untested technologies. British drugmaker AstraZeneca has received $1.2 billion in federal assistance for its vaccine, which uses a harmless virus to provoke an immune response. Moderna Therapeutics, which has received more than $500 million, also has never brought a product to market and is using a genetic technology that is valued for its speed but has never led to a successful human vaccine.

Some say the administration’s strategy — backing a variety of approaches, including some that are cutting-edge but may not work — is the best way to move quickly in the middle of a deadly pandemic. But critics say the public deserves to know more about how taxpayer money is being spent at this critical moment.

“It’s a black box,” said Peter Maybarduk, the director of the global access to medicines program at Public Citizen, a public interest group. “This could be one of the most important medical technologies of our time, and we know very little about how that money is being spent, and what conditions are being placed on it.”

Officials have given varying estimates of how many treatments and vaccines are part of Operation Warp Speed, and have declined to give the full list of which companies are participating. Congress has appropriated nearly $10 billion to support development of a coronavirus treatment or vaccine, but Trump administration officials have said that billions more could ultimately be spent, without providing additional details. A flurry of contracts with vaccine and drug manufacturers were recently made public, but the documents were heavily redacted and provided little information about the arrangements with the companies.

In an interview on Sunday, Novavax’s president and chief executive, Stanley C. Erck, initially said he was not sure where in the government the $1.6 billion was coming from. A Novavax spokeswoman later said the money was coming from a “collaboration” between the Health and Human Services Department and the Defense Department.

“Adding Novavax’s candidate to Operation Warp Speed’s diverse portfolio of vaccines increases the odds that we will have a safe, effective vaccine as soon as the end of this year,” Alex M. Azar II, the health and human services secretary, said in a statement.

Until now, new vaccines have taken years to develop, and many vaccines fail in clinical trials when they turn out to be ineffective or to cause serious side effects. Many experts have said the aggressive timelines set by companies and government officials for a coronavirus vaccine are overly optimistic.

Mr. Erck said Novavax’s coronavirus vaccine uses the same technology as its other experimental vaccines, such as one for the flu, that have been tested in late-stage clinical trials. Novavax has recently brought in senior executives from established manufacturers like AstraZeneca and GlaxoSmithKline, he said.

“The risk they’re taking is that a company like ours — which doesn’t have a pipeline of already commercialized products — can we get to the big leagues and scale up?” he said. “And I think they’re placing the bet that we can.”

The U.S. investment comes after an international group, the Coalition for Epidemic Preparedness Innovations, awarded up to $388 million to Novavax in May to make its coronavirus vaccine available globally.