- AstraZeneca announced Tuesday that the pause was due to a potentially unexplained illness in one of its trials.
- The pharma giant's shares fell more than 6% in after-hours trading Tuesday.
- Its London-listed shares slipped 0.4% as European markets opened on Wednesday.
LONDON — The U.K.'s health minister on Wednesday rushed to defend AstraZeneca's decision to pause a closely-watched coronavirus vaccine trial due to safety concerns, saying that the decision is not necessarily a setback to its development.
AstraZeneca announced Tuesday that the pause was due to a potentially unexplained illness in one of its trials. The pharma giant's shares fell more than 6% in after-hours trading Tuesday and its London-listed shares slipped 0.4% as European markets opened on Wednesday.
"It is obviously a challenge to this particular vaccine," Matt Hancock told Sky News when asked about the pause in the trial of the vaccine which is being developed with Oxford University.
"It's not actually the first time that it's happened to the Oxford vaccine and it's a standard process in clinical trials whenever they find something that they need to investigate," he added.
Asked whether it would set back attempts to find a Covid-19 vaccine, he said: "Not necessarily, it depends on what they find when they do the investigation."
AstraZeneca told CNBC in a statement Tuesday that the pause "is 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."
It said it was trying to expedite the review to "minimize any potential impact on the trial timeline."
"We are committed to the safety of our participants and the highest standards of conduct in our trials," the company said.
Analysts from Jefferies equity research said in a note Wednesday that they "envisage a short-term stock correction which may prove misplaced."
"Temporary pauses in dosing of subjects is standard clinical trial practice and given the expedited path into Phase III (trials) for AZN/Oxford Uni Covid-19 vaccine AZD1222, we believe it is not surprising a serious adverse event triggered a study halt to investigate if drug-related."
AstraZeneca began its trial late last month and is one of three companies currently in late-stage testing for a potential vaccine. The other two are Pfizer and Moderna, which both began their trials in late July.
- CNBC's Berkeley Lovelace Jnr. contributed to this article.