Thursday 26 November 2020 8:47 pm

Astrazeneca mulling extra vaccine trial to 'validate' efficacy after results confusion

Astrazeneca’s chief executive today said that the firm was likely to carry out another trial of its potential coronavirus vaccine after doubts were raised as to its efficacy.

The admission, which was reported by Bloomberg, came after reports that a number of participants had received the wrong dosage during the trials.

Read more: Analysis: Why dismay over the Astrazeneca vaccine is misplaced

When the FTSE 100 group reported the results of its trial on Monday, the vaccine, which is being developed in partnership with Oxford University, was found to have a 90 per cent efficacy rate in one of its data sets.

But celebrations were replaced by confusion when it transpired that the 90 per cent rate referred to a trial in which participants received one half dose and then a full dose of the virus.

The efficacy rate for those who received two full doses, on the other hand, was 62 per cent, for an average of 70 per cent overall.

Concerns grew later when it transpired that the lower doses had been given in error, and to a group of younger participants.

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“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” chief executive Pascal Soriot told Bloomberg.

Instead of adding to the ongoing trial in the US, the new study will instead evaluate the effectiveness of a lower dose of the vaccine that performed better than the full dose in the earlier trial.

Soriot added that he did not think the extra trial would hold up the process of getting the Astrazeneca vaccine approved by regulators in the UK and EU.

A spokesman for Astrazeneca said the firm would work with regulators to investigate the results: “As we communicated earlier this week, there is strong merit in continuing to further investigate the half-dose/full dose regimen.”

“We are further evaluating the data and will work with regulators on the best approach for further evaluation.

“This would add to data from existing trials which are currently being prepared for regulatory submission,” he said.

Read more: Astrazeneca and University of Oxford vaccine 70 per cent effective

Soriot’s comments, which came just before markets closed today, sent the blue-chip’s shares down 0.7 per cent.

Over the course of the week the group’s stock has fallen seven per cent as questions over the trial multiplied.