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.

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AstraZeneca has paused a phase-three trial of its potential COVID-19 vaccine [File: Drago Prvulovic/Reuters]

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 coronavirus vaccine candidates 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,” said Michele Meixell, the company’s spokeswoman.

“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 had suffered a severe adverse reaction to the drug. 

AstraZeneca said that in large trials, illnesses sometimes occur in participants by chance, but that 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,” Meixell said.

The drug is in trials involving thousands of people in the United States, Brazil, South Africa and the UK, where the patient who fell ill is. 

Julie Fischer, an associate research professor in the Department of Microbiology and Immunology at the Center for Global Health Science and Security at Georgetown University, told Al Jazeera such a pause was “part of the process” of drug development and clinical trials.

“For a pause, the event would need to be serious; something related to the heart, lungs, kidneys or other part of the body’s health system that required medical attention and was sufficiently serious to merit a pause to this very important vaccine trial in order to make sure it is safe, and that the adverse effect is not due to the vaccine itself.”  

Florian Krammer, professor of microbiology at the Icahn School of Medicine at Mount Sinai said the fact a patient had fallen ill underscored the need for extensive trials.

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

Clinical trial 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 6 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 – is 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 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.

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 approved 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.

Source: Al Jazeera, News Agencies