LONDON (AP) — The British government has signed a deal with GlaxoSmithKline and Sanofi Pasteur for 60 million doses of a potential coronavirus vaccine that could start to be rolled out in the first half of next year.

Britain’s GSK and France’s Sanofi have the largest vaccine manufacturing capability in the world. The vaccine prospect is based on the existing DNA-based technology used to produce Sanofi’s seasonal flu vaccine.

The government said that if the vaccine proves successful, then priority groups, such as health and social care workers, could be given the first doses as early as the first half of next year.

Human clinical studies of the vaccine will begin in September followed by a phase 3 study in December.

This is the fourth deal the British government has signed for potential coronavirus vaccines, worth a combined 250 million doses.