The health authority of Brazil Anvisa has said that a volunteer in a clinical trial of the COVID-19 vaccine developed by AstraZeneca (LON:AZN)(STO:AZN) and Oxford University had died but added that the trial would continue, Reuters news agency reported on Thursday.

Oxford University confirmed the plan to keep testing, saying in a statement that after careful assessment "there have been no concerns about safety of the clinical trial."

AstraZeneca declined to comment immediately.

Reuters said that a source familiar with the matter told it the trial would have been suspended if the volunteer who died had received the COVID-19 vaccine, suggesting the person was part of the control group that was given a meningitis jab.

According to the Federal University of Sao Paulo, which is helping coordinate phase 3 clinical trials in Brazil, an independent review committee had also recommended the trial continue. The university earlier confirmed the volunteer was Brazilian but gave no further personal details.

So far, 8,000 of the planned 10,000 volunteers in the trial have been recruited and given the first dose in six cities in Brazil and many have already received the second shot, said a university spokesman.

Anvisa provided no further details, citing medical confidentiality of those involved in trials, Reuters added.