Oxford Covid-19 vaccine trial paused after participant falls ill

AstraZeneca is investigating ‘unexplained illness’ to see if it is related to vaccine

AstraZeneca has paused global trials, including large late-stage trials, of its experimental coronavirus vaccine due to an unexplained illness in a study participant.

The vaccine, developed with the University of Oxford, has been described by the World Health Organization as probably the world's leading candidate and the most advanced in terms of development. The suspension dims prospects for an early rollout amid reports that the United States was aiming for a fast-track approval before the November presidential election.

The British drugmaker said it voluntarily paused trials to allow an independent committee to review safety data, and it was working to expedite the review to minimise any potential impact on the trial timeline.

“This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials,” the company said in an emailed statement.


The nature of the illness was not disclosed, although the participant is expected to recover, according to Stat News, which first reported the suspension due to a “suspected serious adverse reaction”.

Advance purchase

Ireland, through the European Commission, was a participant in an advance purchase agreement struck with AstraZeneca for the vaccine. These agreements involve “forward funding” the development of the drug in exchange for early doses when a vaccine becomes available. The deal between the EU and AstraZeneca was the first the bloc struck for a Covid vaccine.

AstraZeneca has signed a similar deal with the US administration.

A Commission spokesman said it is “following this development very closely”.

“It is important to note that the postponement of clinical trials in this instance is something that could normally happen in any clinical trial and a single event is not sufficient for drawing any firm conclusion.”

The spokesman added that safety concerns dictate that “if serious side effects are detected, the vaccine will not be made available for use in the EU.”

Stella Kyriakides, EU Commissioner for Health and Food Safety, said that “while a vaccine represents the surest exit strategy from the Covid-19 pandemic, the safety of citizens is the top priority, and I want to be clear that we would never compromise on this”.

The Department of Health and Department of the Taoiseach had not responded to queries on how much funding Ireland had committed to the agreement at time of publication.

Adverse event

The US Food and Drug Administration defines an adverse event as one in which evidence suggests a possible relationship to the drug being tested.

According to a New York Times report which cited a person familiar with the situation, a participant based in the United Kingdom was found to have transverse myelitis, an inflammatory syndrome that affects the spinal cord and is often sparked by viral infections.

Whether the illness was directly linked to AstraZeneca’s vaccine remains unclear, the report said. AstraZeneca declined to comment on the report.

Shares slide

AstraZeneca's shares fell more than 8 per cent in after-hours US trading, while shares in rival vaccine developer Moderna Inc rose more than 4 per cent. Shares in AstraZeneca's Indian unit, AstraZeneca Pharma India Ltd, tumbled more than 12 per cent.

Called AZD1222, the vaccine is in late-stage clinical trials in the United States, Britain, Brazil and South Africa and additional trials are planned in Japan and Russia. The trials aim to enroll up to 50,000 participants globally.

South Korea said on Wednesday it would look into the suspension and review its plan to participate in the manufacturing of the vaccine.

“It’s not rare that clinical trials get suspended as various factors interact,” health ministry official Yoon Tae-ho told a briefing.

The decision to put the trial on hold has impacted clinical trials being conducted by other vaccine makers, which are looking for signs of similar reactions, Stat said.

The US National Institutes of Health, which is providing funding for AstraZeneca’s trial, declined to comment.

Moderna said in an emailed statement it was “not aware of any impact” to its ongoing Covid-19 vaccine study at this time.

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, Moderna and Pfizer, 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, GlaxoSmithKline, Novavax, Sanofi and BioNTech. – Reuters