The National Health Surveillance Agency (Anvisa) reported this Tuesday on the death of a 28-year-old volunteer who participated in the tests of the vaccine of AstraZeneca Y Oxford against covid-19.

As reported by O Globo, the death was notified on October 19, the causes of death are still being investigated.

It is not clear yet whether the person took the real vaccine or the placebo, this is because tests of this type are carried out using the “double-blind” method, in which neither doctors nor patients initially know which version is supply.

Both the Sinovac and Oxford vaccines are in the final stages of clinical trials in Brazil, one of the largest testing areas due to their high rates of infection.

Both still need regulatory approval.

Brazil already has a previous contract to purchase 100 million doses of the Oxford vaccine, but CoronaVac is expected to be available first, after the British university has suspended its tests when one of its volunteers developed an unexplained disease.

With 212 million inhabitants, Brazil has so far registered 5.3 million infections and almost 155,000 deaths from the new coronavirus.