CAMBRIDGE (CBS) – Cambridge biotech company Moderna says it has approval from the FDA to move into the second phase of its development of a potential coronavirus vaccine.

Moderna has been testing healthy adult volunteers with three doses of the vaccine. Phase two involves two vaccinations and studying those volunteers. They’re hoping to start phase three in early summer.

Moderna is teaming up with Swiss company Lonza to make one billion doses of the vaccine per year, if it is approved.

Public health officials have said it could take 18 months to fully validate a vaccine. Moderna began its work in January.