Coinspeaker PFE Stock Up 2.37%, Pfizer Begins Human Trials of Its COVID-19 Vaccine Candidate in U.S.On Monday, Pfizer announced it had dosed the first participants of the Phase 1/2 clinical trial for the coronavirus vaccine program in the U.S. In general, there will be 360 healthy patients dosed with the vaccine. PFE stock price is rising.PFE Stock Up 2.37%, Pfizer Begins Human Trials of Its COVID-19 Vaccine Candidate in U.S.