On Wednesday, ANVISA, the Brazilian National Health Surveillance Agency, announced that it has been investigating data received on the death of a participant in a coronavirus vaccine trial developed by AstraZeneca and Oxford University.

ANVISA told Medscape Medical News that it was formally informed about the death of the volunteer on October 19. The Brazilian International Security Assessment Committee is now investigating the case.

The officials linked to the study have not confirmed the identity of the participant and the cause of death.

In the email received by Medscape Medical News, ANVISA reiterated that “according to national and international regulations on good clinical practices, data on clinical research volunteers must be kept confidential, in accordance with the principles of confidentiality, human dignity, and protection of participants.”

However, according to O Globo, a Brazilian newspaper based in Rio de Janeiro, said the participant who died is a 28-year-old doctor, who recently graduated and worked as a frontline medical professional treating COVID-19 patients in three hospitals in Rio de Janeiro.

The volunteer reportedly died last Thursday due to COVID-19 complications. However, it is unknown whether the participant received the experimental vaccine or placebo.

Dr. Sergio Cimerman, the president of the Brazilian Society of Infectious Diseases (SBI), said it is important to wait for the results of the investigation because participants may die during any vaccine trial, “even more so in cases in which the final goal is to immunize the population in record time.”

“It is precisely the phase 3 study that assesses efficacy and safety so that the vaccine can be used for the entire population,” Dr. Cimerman said. “We cannot let ourselves lose hope, and we must move forward, as safely as possible, in search of an ideal vaccine.” This article was originally published in the Portuguese edition of Medscape Medical News.