Moderna on Thursday confirmed it plans to start a trial of 30,000 volunteers of its much-anticipated coronavirus vaccine in July as the company enters the final stage of testing.

The Cambridge, Massachusetts-based biotech said the primary goal of the study would be to prevent symptomatic Covid-19, the disease caused by the novel coronavirus. The key secondary goal would be prevention of severe disease, as defined by keeping people out of the hospital.

Moderna said it has selected the 100 microgram dose of the vaccine for the late-stage study. At that dose level, the company is on track to deliver about 500 million doses per year, and possibly up to 1 billion doses per year, starting in 2021 from the company’s internal U.S. manufacturing site and strategic collaboration with Swiss drugmaker Lonza.