During pandemics, adjuvants are especially valuable because they can increase the potency of vaccines, allowing companies to produce more doses from each batch it manufactures. Glaxo's adjuvant, called AS03, is a combination of vitamin E and liver oil taken from sharks. The company used it to enhance the effectiveness of its vaccine for the H1N1 pandemic in 2009.

To find partners for its adjuvant, Glaxo launched an internal project led by a team of Glaxo drug hunters who looked for anyone working on a key vaccine component -- a protein known as an antigen -- that would cause a person's immune system to build up defenses against the new coronavirus. The hope was that people who got the antigen through vaccination would develop antibodies and perhaps other defenses that could protect against Covid-19.

Glaxo's drug hunters mapped every antigen in the works for Covid-19 using squares on a PowerPoint slide. Every square contained the name of a potential partner, details about the vaccine and a contact person who had spoken with Glaxo. The slide resembled a digital quilt, with some 100 squares.

Some in the quilt approached Glaxo seeking help. Glaxo reached out to others. The campaign was "quite unusual for us," says Mr. Connor. "Going out and offering it to the world was something quite, quite different."

On that first call with Sanofi, Mr. Connor said he remembers telling Mr. Loew: "'There is an opportunity here for us to do something together, which means that we could ultimately go faster for the world and make a difference to the common enemy, which is the virus itself.'"

Within 36 hours, they agreed to create a joint task force that would start exchanging information and planning how to make the partnership work while the companies worked out a formal agreement. "We knew that the world was waiting," Mr. Connor says.

Initial meetings, held by videoconference among employees across multiple time zones, were "slightly awkward" as the rivals turned teammates felt each other out, said Thomas Triomphe, Sanofi's executive vice president for vaccines.

The companies hope to have results from early-stage studies in late November or early December, Mr. Triomphe said. They aim to start a 30,000-person study by the end of the year and to have the vaccine approved in the first half of 2021, he says.

"When you're facing a public-health crisis there is no team with a blue T-shirt and a team with an orange T-shirt. Very quickly, there was only one team," Mr. Triomphe said.

(END) Dow Jones Newswires

10-24-20 0015ET