A volunteer participating in clinical trials of the COVID-19 vaccine developed by Oxford University has died in Brazil, officials announced, though media reports said he had received a placebo, not the test vaccine.
It is the first death reported in the various coronavirus vaccine trials taking place worldwide.
However, organizers of the study on Wednesday said an independent review had concluded there were no safety concerns and that testing of the vaccine, developed with pharmaceutical firm AstraZeneca, would continue.
Media reports said the volunteer was a 28-year-old doctor working on the front lines of the pandemic who died of complications from COVID-19.
Brazilian newspaper Globo and international news agency Bloomberg said he was in the control group and had received a placebo rather than the test vaccine, citing sources close to the trials.
"Following careful assessment of this case in Brazil, there have been no concerns about safety of the clinical trial, and the independent review in addition to the Brazilian regulator have recommended that the trial should continue," Oxford said in a statement.
AstraZeneca said medical confidentiality meant it could not give details on any individual volunteer, but that independent review had "not led to any concerns about continuation of the ongoing study."
Trials can't detect risk reduction—study
Writing in the BMJ medical journal, associate editor Peter Doshi warned that not even Phase 3 trials under way in the race for a vaccine can prove their product will prevent people contracting COVID-19.
In a sobering essay, Doshi said those hoping for a breakthrough to end the pandemic would be disappointed, with some vaccines likely to reduce the risk of COVID-19 infection by only 30 percent.
"None of the trials currently under way are designed to detect a reduction in any serious outcome such as hospital admissions, use of intensive care, or deaths," he wrote.
"Nor are the vaccines being studied to determine whether they can interrupt transmission of the virus."
The World Health Organization has identified 42 candidate vaccines in clinical trials, ten of which are in the most advanced "phase 3" stage.
Ireland became the first European country to enter a second national lockdown and Germany's daily cases leapt to a record high as the second wave of coronavirus spread gloom across the continent on Thursday.
As a COVID-19 surge gripped European countries ahead of the onset of winter, Spain added to the list of disquieting statistics when it became the first country to pass a million cases.
Ireland's five million people have been ordered to stay at home for six weeks, with non-essential businesses urged to shut up shop.
Irish authorities have also imposed a strict five-kilometer travel limit, limited bars and restaurants to takeaway only and extended a ban on visits between households.
Germany, once a European success story for its virus response, leapt to a record 11,287 new infections in 24 hours, soaring past the previous high of just over 7,800 set last Friday.