A U.S. study of a potential COVID-19 vaccine is being expanded to include older adults, the age group most at risk from the new coronavirus. The National Institutes of Health and Moderna already are testing an experimental shot in healthy young and middle-aged adults in Seattle and Atlanta. Moderna announced Thursday the study also will allow seniors to volunteer. A different vaccine candidate is further along in testing in China. A third, made by Inovio Pharmaceuticals, just began U.S. testing and received funding to start a similar study in South Korea.
