AstraZeneca puts COVID-19 vaccine trial on hold over safety concern

"As part of the ongoing randomised, 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," the spokeswoman 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. In large trials illnesses will happen by chance but must be independently reviewed to check this carefully."

The study is testing the COVID-19 vaccine being developed by AstraZeneca and University of Oxford researchers at sites including the United States and the United Kingdom, where the adverse event was reported.

The nature of the safety issue and when it happened were not immediately known, although the participant is expected to recover, according to Stat News.

AstraZeneca declined to comment on whether the pause would cause any delays on when the product would be available for distribution, or whether Australia would have to wait longer for its doses.

Earlier this week AstraZeneca and CSL both said doses of the product could be ready in Australia in the early part of 2021.

"We are working to expedite the review of the single event to minimise any potential impact on the trial timeline," the AstraZeneca spokeswoman said.

World-leading immunologist Professor Peter Doherty says it is not uncommon for vaccine trials to be halted due to an adverse health reaction is hopeful the hiccup will not stall the vaccine’s development.

He said it was "pretty much expected" for a trial member to develop a health problem while trialling the vaccine. He said it was too early to cast judgement on the seriousness of the reaction because details have not yet emerged about what the reaction was.

"I don’t think it’ll slow it down much … unless there’s a real indication there’s a safety issue," he said on ABC radio.

"I don’t think we’re anything near that stage."

The Stat report said suspension of the trial was having an impact on other AstraZeneca vaccine trials - as well as on clinical trials being conducted by other vaccine makers.

Nine leading US and European vaccine developers pledged on Tuesday to uphold scientific safety and efficacy standards for their experimental vaccines despite the urgency to contain the coronavirus pandemic.

The companies, including AstraZeneca, Pfizer and GlaxoSmithKline, issued what they called a "historic pledge" after a rise in concern that safety standards might slip in the face of political pressure to rush out a vaccine.

The companies said they would "uphold the integrity of the scientific process as they work towards potential global regulatory filings and approvals of the first COVID-19 vaccines.".

The other signatories were Johnson & Johnson, Merck & Co, Moderna, Novavax, Sanofi and BioNTech.

with Paul Sakkal, wires