The global Oxford University Covid-19 vaccine trial has been suspended after a participant in the UK had a suspected adverse reaction.
Oxford and AstraZeneca are among the frontrunners in the race to provide a jab that immunises against Covid-19.
Their vaccine cleared phase 1 and 2 human trials and progressed to the third phase where it was being tested on participants internationally.
However, testing of the jab has been suspended after a participant, believed to be in the UK, developed an unexplained illness, it emerged on Tuesday night.
A spokesperson for AstraZeneca confirmed testing has been put on hold.
They said the company’s “standard review process triggered a pause to vaccination to allow review of safety data”.
A source told Stat News, the injured participant is expected to recover. The decision to pause the trial was made out of “an abundance of caution”, they added.
The spokesperson said the suspension was “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.”
The pharmaceutical company made the voluntary decision to pause the trial and an independent team has been drafted in to review the incident. Clinical holds are not uncommon during vaccine trials
It is unclear how long the trial will be put on hiatus. AstraZeneca said it is working to “expedite the review of the single event” to minimise disruption to the trial timeline.
As recently as Monday, the Health Secretary said the vaccine could be ready by “the early months of next year”, adding that production on the UK’s batch has already begun – well ahead of any approval being granted.
AstraZeneca, has committed to producing two billion doses by next summer.
Phase 1 of the Oxford trial showed promising results as Oxford scientists discovered their jab triggered a response that may offer a “double defence” against the virus. The results were hailed at the time as “a really important milestone”.