AstraZeneca has put its clinical trial of a vaccine for COVID-19 on hold.  U-W Hospital was one of the worldwide sites for the work that started last week.  Tuesday’s move was made after a participant in the United Kingdom suffered what was suspected to be a serious adverse reaction.  The reaction hasn’t been described.  U-W Health chief quality officer Doctor Jeff Pothoff says it is common for trials like this one to be temporarily halted.  Madison enrollment is on hold and people scheduled to get the vaccine this week have been notified their appointments are canceled.