Oxford University Covid vaccine trial put on hold due to possible adverse reaction in participant

https://www.theguardian.com/world/2020/sep/09/oxford-university-astrazeneca-covid-vaccine-trial-put-on-hold-due-to-adverse-reaction-in-participant

https://www.pennlive.com/coronavirus/2020/09/astrazeneca-covid-19-vaccine-study-paused-after-potentially-unexplained-illness.html