Gritstone Bio, a cancer and infectious disease drug developer has won a contract from the US government to test its experimental COVID vaccine against an approved coronavirus shot in a headto head study. The contract announced Wednesday  is part of the Project NextGen an initiative launched by the US Department of Health and Human Services to bring new COVID drugs and vaccines to market. Gritstone will conduct a doubleblind Phase 2b study of its self amplifying messenger RNA vaccine in a study of 10000 people