The US government will pay $2.1 billion to Sanofi SA and GlaxoSmithKline Plc to get COVID-19 vaccines to pay 50 million individuals and to underwrite the drug manufacturers' testing and manufacturing, the companies said on Friday.

The award is the biggest yet from'Operation Warp Speed', the White House initiative aimed at accelerating access to treatments and vaccines to fight COVID-19, the respiratory disease caused by the publication coronavirus.

The agreement, announced by the US Department of Health and Human Services and Department of Defense, operates out in a cost of about $42 per person inoculated.

That's almost equal to the $40 per individual the US agreed to cover Pfizer Inc and BioNTech SE when it inked a nearly $2 billion deal to 50 million classes of that potential vaccine last week.

The Sanofi-GSK deal is for 100 million doses, at two each individual, and gives the government an choice to purchase an additional 500 million doses at an unspecified price.

Sanofi executive Clement Lewin said the companies had not yet agreed with the government on a specific cost for the additional doses.

GSK stated in an announcement that over half the total funding will go into further development of the vaccine, such as clinical trials, with the remainder used for a production ramp-up and delivery of dosages.

The two companies' inoculation is combination of a vaccine according to Sanofi's flu shots and a complementary technology from GSK known as an adjuvant, designed to enhance the vaccine's potency.

Sanofi will receive the bulk of the profits from the deal.

It marks the second contract for the Franco-British group's vaccine candidate once they agreed earlier this week to supply 60 million doses into the British government.

Reuters reported last week that Pfizer's deal was expected to set a pricing benchmark for future prices between drugmakers and governments.

Moderna Inc and Pfizer began two 30,000-subject trials of COVID-19 vaccines on Monday that may clear the way for regulatory approval and use at the end of 2020.