AstraZeneca COVID-19 vaccine trial on hold over safety issue


A serious adverse reaction in a volunteer has triggered the safety protocol for the large-scale trial.

AstraZeneca has “voluntarily paused” late-stage trials of the highly-anticipated COVID-19 vaccine it is developing with the University of Oxford after one of the study volunteers developed an unexplained illness, the company said on Wednesday.

The AstraZeneca-Oxford vaccine is seen as one of the most promising of the vaccines against coronavirus that are currently under development.

“As part of the ongoing randomized, controlled global trials of the Oxford coronavirus vaccine, our standard review process was triggered and we voluntarily paused vaccination to allow review of safety data by an independent committee,” a spokesperson said.


“This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials.”

Health news website Stat News earlier reported that the trial would be suspended because a volunteer in trial had suffered a severe adverse reaction to the drug.

AstraZeneca said that in large trials, illnesses would sometimes happen by chance but the issue had to be reviewed independently.

“We are working to expedite the review of the single event to minimise any potential impact on the trial timeline,” the spokesperson said.

The drug in in trials in a number of countries including the United States and Brazil and It was not immediately clear where the patient was or the nature and severity of the illness.

Florian Krammer, Professor of Microbiology at the Icahn School of Medicine at Mount Sinai said the illness could turn out to be trivial, serious, related or unrelated to the vaccine, and underscored the need for extensive trials.

“It shows you that the evaulation process works, and why we need Phase III trials,” he wrote on Twitter.

Clinical holds are not uncommon, but AstraZeneca’s is the first phase-three COVID-19 vaccine trial known to have been put on hold. It is unclear how long the suspension might last and shares of the company fell more than six percent in after-hours trading on the New York Stock Exchange.

The progress of the company’s trial – and those of all COVID-19 vaccines in development – are being closely watched given the pressing need for new ways to curb the global pandemic. There are currently nine vaccine candidates in Phase III trials.
Safety protocols

Separately, nine leading US and European vaccine developers promised on Tuesday to uphold the scientific standards in the global race to contain the pandemic.

The companies, including Pfizer, GlaxoSmithKline and AstraZeneca, in a joint statement made a “historic pledge … to uphold the integrity of the scientific process as they work towards potential global regulatory filings and approvals of the first COVID-19 vaccines”.

The unusual move to promise to play by well-established rules underlines the highly politicised debate over what action is needed to rein in the spread of the disease.

COVID-19 vaccine: Safety concerns as countries rush for cure

The head of the Food and Drug Administration, the US regulator, said last month that the normal approval process could be bypassed for a COVID-19 vaccine if officials were convinced the benefits outweighed the risks. The comments prompted a call for caution from the World Health Organization.

Developers globally have yet to produce large-scale trial data showing actual infections in participants, but Russia granted approval for a COVID-19 vaccine last month, prompting some Western experts to criticise a lack of testing.

The head of China’s Sinovac Biotech said most of its employees and their families have already taken an experimental vaccine developed by the Chinese firm under the country’s emergency-use programme.



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