The European pharmaceutical giants are combining their resources to develop a Covid-19 vaccine and aim to produce a batch within the next 20 months.
"If we're successful ... we're hoping to get to hundreds of millions of doses by the end of next year," she said in an interview set to air on "Mad Money." "But, a lot of work to do, and we're sure the world will need more than one vaccine, considering the state of demand."
The effort is an example of how drugmakers around the globe are teaming up to fight the coronavirus pandemic, which has infected nearly 2 million people worldwide. GSK is a British company, and Sanofi is based in France.
The two companies are "leaders who are both bringing proven pandemic technologies and scale to develop, hopefully, an adjuvant vaccine against Covid-19," Walmsley said.
Vaccine development typically takes 10 years to be finalized for mass use, but scores of companies are rushing to have one ready in 12 to 18 months. Dozens of candidate vaccines are now underway, and three are reportedly in clinical trials, or the human testing phase.
As part of the deal, which is expected to be hashed out in full within weeks, Sanofi will supply its Covid-19 antigen, a genetic match to proteins in the fast-spreading virus, and GSK will supply its pandemic adjutant technology, which could enhance the immune response.
"As the world faces this unprecedented global health crisis, it is clear that no one company can go it alone," Sanofi CEO Paul Hudson said in a statement. "That is why Sanofi is continuing to complement its expertise and resources with our peers, such as GSK, with the goal to create and supply sufficient quantities of vaccines that will help stop this virus."
Clinical trials are scheduled to begin later this year.
The global count of coronavirus cases exceeded 1.97 million as of Tuesday afternoon.