AstraZeneca Plc received more than $1 billion in U.S. government funding to develop a Covid-19 vaccine from the University of Oxford, and said it has supply agreements for 400 million doses.

The investment accelerates a race to secure vaccine supplies, seen as a key step toward getting global economies moving again after a lockdown-induced slump. Stock markets have been rising and falling on developments in research labs, as investors weigh the prospects for a successful shot.

The U.K. drugmaker received the money from the U.S. Biomedical Advanced Research and Development Authority and said it has secured capacity to make 1 billion doses. The move comes as the company’s vaccine candidate is still in human trials, with no guarantee of success.