Brazilian health authorities with the country's health regulator, Anvisa, said Wednesday they received a report that a volunteer with a clinical trial for a COVID-19 vaccine has died.
The participant for the vaccine study, developed by AstraZeneca and Oxford University, died while participating in the study and an investigation was still ongoing Wednesday to find out more details regarding the cause of death, Reuters reported.
As Bloomberg noted, it was unclear at first from the reports if the study participant received an actual dose of the vaccine or if the person received a placebo. A later report from Bloomberg said that the study participant did not receive the company's vaccine, citing a "person familiar with the matter."
Meanwhile, AstraZeneca shares turned negative at one point Wednesday after reports of the incident, CNBC reported.
This is a breaking news story and will continue to be updated.