GSK, Sanofi restart testing for COVID-19 vaccine after delay By (0) "We are confident our vaccine candidate has strong potential and we are very encouraged by the latest preclinical data," a pharma executive said of the vaccine Monday. File Photo by EPA-EFE Feb. 22 (UPI) -- Pharma companies GlaxoSmithKline and Sanofi announced Monday that they have begun a second-stage clinical trial for their protein-based COVID-19 vaccine, after testing was delayed in December. The drugmakers said more than 700 volunteers are involved in the Stage 2 testing for its protein-based adjuvanted coronavirus vaccine. Advertisement GSK and Sanofi delayed trials in December after finding that the vaccine wasn't promoting enough of an immune response in older people. Monday's announcement said developers improved the vaccine formulation and the new testing phase includes older adults.