AstraZeneca's vaccine -- the leading one in the world -- also known as Oxford vaccine or Chadox1, was being tested in Brazil.
A 28 year medical student in Brazil volunteered for it.
News today : He died after being injected with the vaccine.
.
https://www.cnbc.com/2020/10/21/astrazeneca-shares-slide-after-brazilian-health-authority-says-volunteer-in-covid-vaccine-study-dies.html