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COVID-19 vaccine trials evaluating mostly mild cases, not designed to prove they can save lives: Expert

COVID-19 vaccine trials evaluating mostly mild cases, not designed to prove they can save lives: Expert

Transmission electron microscope image shows SARS-CoV-2, that causes COVID-19.

PARIS: The COVID-19 vaccine trials currently being carried out evaluate mostly mild cases and are not designed to prove they can save lives or help the most vulnerable, a leading public health expert said on Wednesday (Oct 21).

The World Health Organization (WHO) has identified 42 candidate vaccines in clinical trials, 10 of which are in the most advanced Phase 3 stage.

This is where a vaccine's effectiveness is tested on a large scale, generally tens of thousands of people across several continents.

But even the most advanced trials are evaluating mild rather than severe disease, said Peter Doshi, assistant professor of pharmaceutical health services research at the University of Maryland School of Pharmacy.

"None of the vaccine trials are designed to detect a significant reduction in hospital admissions, admission to intensive care, or death," wrote Doshi in the BMJ medical journal.

READ: Chinese city to offer COVID-19 vaccine candidate as emergency use expands


Doshi, who is also associate editor of the journal, said that vaccine protocols "should be scrutinised by the widest possible readership" and questioned if the right end points are being studied.

He added rather than studying severe disease, the primary end point of symptomatic COVID-19 in current "mega-trials" is set at "any severity".

"A laboratory positive result plus mild symptoms such as cough and fever count as outcome events. These studies seem designed to answer the easiest question in the least amount of time, not the most clinically relevant questions," said Doshi.

READ: Volunteer in AstraZeneca COVID-19 vaccine test dies in Brazil


This may be down to the numbers of people involved in trials, he said, pointing out that the majority of confirmed COVID-19 infections involve mild 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 at-risk constituency.

Without enrolling frail and elderly volunteers in trials in sufficient numbers, Doshi said there can be little basis for assuming any benefit against hospitalisation or mortality.

He added that children, immunocompromised people and pregnant women had largely been excluded from trials, making it unlikely that the experiments will address key gaps in understanding how COVID-19 develops differently among individuals.

"Sixty years after influenza vaccination became routinely recommended for people aged 65 or older in the US, we still don’t know if vaccination lowers mortality," he wrote. 

"Randomised trials with this outcome have never been done.

"Observational studies with results in both directions can be cited, and without definitive randomised evidence the debate will go on. Unless we act now, we risk repeating this sorry state of affairs with COVID-19 vaccines."

READ: US likely to have enough COVID-19 vaccines for all vulnerable Americans by year end: Official​​​​​​​

Several trials have already been halted after participants became ill.

Many countries plan to prioritise vulnerable people once a vaccine is available, but Doshi said that those hoping for a miracle end to the pandemic would have to wait.

He said that several pharmaceutical firms had designed their studies "to detect a relative risk reduction of at least 30 per cent in participants developing laboratory confirmed COVID-19".

Recent studies have also confirmed that it is possible for someone to be reinfected with COVID-19, a development that may impact how governments' form their vaccination plans.

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Source: CNA/afp/mi(aj)


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