(AP) -- A U.S. company says it's on track to begin a huge study next month to prove if its COVID-19 vaccine candidate really works.
The news comes at the same time that Brazil will help with final testing of a different shot from China.
Shots made by Moderna Inc. and the National Institutes of Health and by China's Sinovac work in different ways.
Moderna plans a study of 30,000 U.S. volunteers while researchers in Sao Paulo, Brazil, will recruit 9,000 people to receive Sinovac shots.
About a dozen candidates are in early stages of human testing in the global race for a vaccine.