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PARIS – None of the COVID-19 candidate vaccine trials can detect a reduction in serious outcomes such as hospitalization or death, a leading public health expert said Thursday.
In an article in the medical journal BMJ, Associate Editor Peter Doshi cautioned that not even ongoing Phase 3 trials in the race for a vaccine can demonstrate that their product will prevent people from contracting COVID-19.
In a sobering trial, Doshi said that those hoping for a breakthrough to end the pandemic will be disappointed, as some vaccines will likely reduce the risk of COVID-19 infection by just 30 percent.
“None of the currently ongoing trials are designed to detect a reduction in any serious outcomes, such as hospital admissions, use of intensive care or deaths,” he wrote.
“Nor are vaccines being studied to determine if they can interrupt transmission of the virus.”
The World Health Organization (WHO) has identified 42 candidate vaccines in clinical trials, ten of which are in the most advanced stage of “phase 3”.
This is where the efficacy of a vaccine is tested on a large scale, usually tens of thousands of people on various continents.
But Doshi, an assistant professor of pharmaceutical health services research at the University of Maryland School of Pharmacy, said that even the most advanced trials evaluate mild rather than severe disease.
This may be due to the number of people involved in the trials, he said, noting that the majority of confirmed COVID-19 infections involve little or no symptoms.
And few, if any, of the current trials are designed to find out whether there is a benefit among the elderly, a key sector at risk.
Without enrolling frail and elderly volunteers in the trials in sufficient numbers, Doshi said there may be little basis for assuming any benefit against hospitalization or mortality.
He added that children, immunosuppressed people, and pregnant women had been largely excluded from the trials, so the experiments are unlikely to address key gaps in our understanding of how COVID-19 develops differently between people.
Vaccine test volunteer dies
Several trials have already stopped after participants got sick.
In Brazil, a volunteer participating in clinical trials of the COVID-19 vaccine developed by the University of Oxford has died, authorities announced Wednesday, although media reports said he had received a placebo, not the test vaccine.
It is the first death reported in the various coronavirus vaccine trials being carried out around the world.
However, study organizers said an independent review had concluded that 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 from complications from COVID-19.
The Brazilian newspaper Globo and the international news agency Bloomberg said he was in the control group and had received a placebo instead of the test vaccine, citing sources close to the trials.
“After careful evaluation of this case in Brazil, there have been no concerns about the safety of the clinical trial, and the independent review, in addition to the Brazilian regulator, has recommended that the trial continue,” Oxford said in a statement.
AstraZeneca said medical confidentiality meant that it could not provide details on any individual volunteers, but that the independent review “did not raise concerns about the continuation of the ongoing study.”
30% risk reduction
Many countries plan to prioritize vulnerable people once a vaccine is available, but Doshi said those hoping for a miraculous end to the pandemic would have to wait. He said that several pharmaceutical companies had designed their studies “to detect a relative risk reduction of at least 30 percent in participants who develop laboratory-confirmed COVID-19.”
Recent studies have also confirmed that it is possible for someone to be reinfected with COVID-19, a development that can affect the way governments form their vaccine.
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