(Sharecast News) - AstraZeneca paused the phase three clinical trial of the Covid-19 vaccine candidate that it was developing in conjunction with the University of Oxford, in response to a possible unexplained illness in one of the participants.
The news was first reported by STAT News, which cited a company spokesperson according to whom a "standard review process triggered a pause to vaccination to allow review of safety data".
"In large trials, illnesses will happen by chance but must be independently reviewed to check this carefully," the spokesperson reportedly also explained.
The pause in the study being conducted across the US followed a suspected serious adverse reaction in a participant participant located in the UK.
The nature of the adverse reaction and when it occurred also remained unknown, as did the possible length of the company's decision to hold.
However, AstraZeneca said that it was expediting the review of the "single event" so as to minimise its potential impact on the expected timeline for the trial.
One source cited by STAT News said the hold was decided upon out of an "abundance of caution", while a second source said that it was impacting other trials being conducted by AstraZeneca, as well as those being conducted by other pharmaceutical companies.
STAT News also reported that the participant was expected to recover.
As of 0056 BST, American Depositary Receipts of AstraZeneca were trading 8.04% lower to $50.35.
Futures on the S&P 500 meanwhile were pointing 10.25 points lower to 3,325.25.