Coronavirus vaccine put on hold after volunteer 'suffers adverse reaction'

A leading coronavirus vaccine developer has been forced to hold a late-stage trial after a UK volunteer candidate suffered a suspected serious adverse reaction.

AstraZeneca Plc – which is working alongside the University of Oxford – has confirmed it had had to pause development of the vaccine “to allow review of safety data”.

It is unclear whether the vaccine front runner made the decision itself or was ordered by a regulatory agency, reports Stat News.

The nature of the adverse reaction or when it occurred are not known but the participant is reportedly expected to recover.



The AstraZeneca spokesperson went on to describe the pause as a “routine action” which must happen whenever a “potentially unexplained illness” occurs in one of its trials.

They said during the investigation it is crucial it “maintain[s] the integrity of the trials”, adding the company is working to “expedite the review of the single event” in order to “minimise any potential impact” on the trial’s timeline.

Stat News reports a source told reporters researchers were told the hold has been imposed as “an abundance of caution” while another said it has also impacted other vaccine trials being undertaken by the company and other manufacturers.



It comes on the same day the nine leading US and European vaccine developers pledged to uphold the scientific standards their experimental immunisations will be held against during the race to contain Covid-19.

The companies, including Pfizer, GlaxoSmithKline as well as AstraZeneca, issued what they called a “historic pledge” on Tuesday after a rise in concern that safety and efficacy standards might slip in the rush to find a vaccine.

The companies said in a statement 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.

The promise to play by established rules underlines a highly politicised debate over what action is needed to rein in Covid-19 quickly and to jumpstart global business and trade.

AstraZeneca’s is the first Phase 3 Covid-19 vaccine trial of the nine front runners known to have been put on hold.

It only began its late stage trial in the US in late August, with 62 sites earmarked – while others were started in the UK, Brazil and South Africa.

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