The U.S. government, Sanofi (SNY) and GSK (GSK) on Friday announced a $2.1 billion deal for 100 million doses of its recombinant protein-based coronavirus vaccine. The agreement included an option to purchase an additional 500 million doses.

The companies said they are collaborating with the U.S. Department of Health and Human Services and the Department of Defense to fund the development of the vaccine and the scale of production to mass-produce it once it receives Food and Drug Administration approval.

“The global need for a vaccine to help prevent COVID-19 is massive, and no single vaccine or company will be able to meet the global demand alone ,” Thomas Triomphe, executive vice president and global head of Sanofi Pasteur, said in a statement.

“From the beginning of the pandemic, Sanofi has leveraged its deep scientific expertise and resources to help address this crisis, collaborating with the U.S. Department of Health and Human Services to unlock a rapid path toward developing a pandemic vaccine and manufacturing at large scale. With our partner GSK, we expect our Phase 1/2 study for the recombinant adjuvanted approach to start in September,” Pasteur added.

The Phase 1/2 trials are expected to be followed by Phase 3 clinical trials at the end of 2020. If successful, U.S. regulatory approval is anticipated in the first half of 2021. The companies expect to produce 1 billion doses of the vaccine per year globally.

The race to produce an effective COVID-19 vaccine is moving at a record pace as most vaccines take a decade to develop, CNBC said. One of the fastest vaccines ever developed was for the mumps. It was developed in four years, coming to market in 1967. 

Dr. Anthony Fauci, the nation's top infectious disease expert, told a House hearing Friday he expects to see a viable vaccine by the end of the year.

Sanofi and GSK joined forces in April to provide a COVID-19 vaccine by the end of 2021. The U.S. government has also entered into a $1.95 billion deal with Pfizer and BioNTech to produce 100 million doses of a COVID-19 vaccine when approved.

“The portfolio of vaccines being assembled for Operation Warp Speed increases the odds that we will have at least one safe, effective vaccine as soon as the end of this year,” HHS Secretary Alex Azar, said in a statement . “Today’s investment supports the Sanofi and GSK adjuvanted product all the way through clinical trials and manufacturing, with the potential to bring hundreds of millions of safe and effective doses to the American people.”

The U.S. has recorded 4.49 million positive cases of the coronavirus and more than 152,000 COVID-19 deaths, Johns Hopkins University said.

Shares of Sanofi were trading at $53.00 as of 9:33 a.m. ET, up 50 cents or $0.95, while shares of GSK were trading at $40.91, up 66 cents or 1.64%.