One of the leading producers of a potential coronavirus vaccine has halted trials after a participant in the UK took unwell due to a suspected adverse reaction.
AstraZeneca, which has been working with the University of Oxford, paused production of the drug due to the incident.
The severity of the side-effect is unclear but the patient is reportedly expected to recover, according to the Mirror.
The UK Government announced an agreement with AstraZeneca to produce 100 million doses for the UK in total in July this year.
A spokesperson for the pharmaceutical giant described the decision to halt the production as “routine” when a “potentially unexplained illness” takes place during a trial.
It is unclear if the company took the decision itself or if it was forced to by a regulatory body.
AstraZeneca 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.
