(Reuters) - The U.S. government has cut deals with Johnson & Johnson JNJ.N and Moderna Inc MRNA.O and said it is in talks with at least two other companies to prepare them to produce massive quantities of coronavirus vaccines even before safe and effective ones become available.

There are currently no approved treatments or vaccines specifically for COVID-19, the respiratory disease that has killed more than 35,000 people and infected over 745,000 globally in just a few months.

No vaccine is expected to be ready for use until at least 2021, as they must still be widely tested in humans before being administered to hundreds of millions, if not billions, of people to prevent infection.

On Monday, J&J announced a $1 billion deal with the U.S. government to create enough manufacturing capacity to make more than 1 billion doses of a vaccine, and its shares closed up 8% at $133.01.

It has chosen a candidate but will not begin testing it in people until September.

Moderna, which this month began very early tests of its vaccine candidate in people, also signed a deal with the Biomedical Advanced Research and Development Authority (BARDA), part of the U.S. Department of Health and Human Services.

The arrangements are part of the federal government’s effort to encourage drugmakers to be able to produce massive amounts of COVID-19 vaccines even before any are proven to work.

The J&J effort will be funded in part by about $420 million from BARDA. The agency told Reuters it also plans to spend an unnamed amount to ramp up manufacturing for Moderna’s COVID-19 vaccine candidate.

Moderna shares rose 1.4% to $30.48.

BARDA ultimately plans to support five or six experimental vaccine candidates, with the hopes of having two or three successful ones, BARDA director Rick Bright said in a phone interview.

Experts have estimated it could be 12 to 18 months before a safe and effective vaccine wins regulatory approval.

“Government and industry is working in unprecedented ways,” Bright said. The hope is to work “as quickly as possible and manufacture enough of it for us and the rest of the world in a very short timeframe.”

The agency plans to take over manufacturing of Moderna’s vaccine candidate to enable the Cambridge, Massachusetts-based biotech to focus on testing it in larger trials.

BARDA hopes to speed up the back end of the vaccine manufacturing process, which involves ensuring that they are made and packaged according to standards set by the U.S. Food and Drug Administration.

‘A LOT OF RISK INVOLVED’

There are dozens of coronavirus vaccines in development, according to the World Health Organization. But it is still not clear that people develop lasting immunity to this virus, or what it will take for a vaccine to be protective.

“What you need to do is take an assessment of what the most likely candidates are and invest at risk in those,” said Seth Berkley, chief executive of the Global Alliance for Vaccines and Immunization (GAVI).

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The earlier you make that decision, the more likely you are to have manufacturing in place, but the less confident you are about whether the vaccine will work, Berkley said.

Typically, decisions on whether to move forward with a vaccine are made after safety trials and preliminary efficacy trials have been completed.

J&J said it will begin human testing in September, with an eye toward having a vaccine ready under an emergency use authorization in early 2021.

J&J Chief Scientific Officer Dr. Paul Stoffels told Reuters the company had to start ramping up manufacturing capacity now, even before it has a signal that its experimental vaccine candidate works.

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“That is the only option for us to get it on time,” Stoffels said of the early 2021 target. J&J hopes to have data proving its vaccine works by the end of this year.

J&J has a manufacturing plant in the Netherlands that can make up to 300 million doses of vaccine, Stoffels said, but that “absolutely will not be sufficient for the world.”

The company is also scouting for manufacturing plants in other parts of Europe and Asia capable of making the type of vaccine the company is working on.

Stoffels said J&J’s vaccine will be based on the same technology used to make its Ebola vaccine, which has been widely used in people. The company believes it will prove safe.

In lab studies, it has produced strong neutralizing antibodies to the virus - the type needed to make a successful vaccine.

In addition to the investments in J&J and Moderna, Bright said his agency is in talks with at least two other large vaccine makers, but declined to make them public.

BARDA is interested in working with a broad range of vaccine technologies and with companies that have proven track records, Bright said.

“There’s a lot of risk involved in making a new vaccine, a lot of risk in going quickly,” Bright said. “Wherever possible, we need to understand and mitigate that risk.”