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.
"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's vaccine division, 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."
Public health officials say there is no returning to "normal" until there is a vaccine against the coronavirus, which has infected more than 17 million people worldwide and killed at least 667,808, according to data compiled by Johns Hopkins University. More than 150 vaccines are under development, according to the World Health Organization, with 25 already in clinical trials.
It's a record-breaking time frame for a process that normally takes about a decade to develop an effective and safe vaccine. The fastest-ever vaccine development, for mumps, took more than four years and was licensed in 1967.
Sanofi and GSK announced April 14 that they had entered an agreement to jointly create a Covid-19 vaccine by the end of next year. To make it, Sanofi said it would repurpose technology it uses in flu vaccines while GSK would provide adjuvant technology designed to enhance the immune response in vaccines.
Sanofi is leading the clinical development of the potential vaccine and expects an early-stage human trial to begin in September, followed by a late-stage trial by the end of the year. If the vaccine proves to be safe and effective, the companies expect to request regulatory approval in the first half of 2021.
The announcement comes less than two weeks after the U.S. government said it would pay Pfizer and biotech firm BioNTech $1.95 billion to produce 100 million doses of their vaccine if it proves safe and effective.
On Thursday, senior administration officials at the Department of Health and Human Services said on a conference call that Pfizer and competitor Moderna, which began a phase three trial for its leading vaccine candidate on Monday, have already vaccinated "several hundred people" within the first few days.
HHS Secretary Alex Azar said in a statement Friday the portfolio of vaccines being assembled for the U.S. increases the odds that "we will have at least one safe, effective vaccine as soon as the end of this year."
"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."