AstraZeneca has defended its use of Covid-19 vaccine data after US authorities suggested the company may have used “outdated information” in its results.
AstraZeneca said results showed that its vaccine was 79% effective against coronavirus and 100% effective against severe disease, figures that were stood up in all of the data it had looked at.
In a statement, the pharmaceutical giant said: "The numbers published yesterday were based on a pre-specified interim analysis with a data cut-off of February 17.
"We have reviewed the preliminary assessment of the primary analysis and the results were consistent with the interim analysis. We are now completing the validation of the statistical analysis.
"We will immediately engage with the DSMB to share our primary analysis with the most up-to-date efficacy data."
In a statement released late on Monday, the US Data and Safety Monitoring Board (DSMB) raised concerns about the trial.
Among the vaccinated volunteers in the trial, there were no severe illnesses or hospital admissions.
There were five cases of severe illness or hospital admission among the volunteers who received dummy shots.
These results are consistent with findings from Britain and other countries that the vaccine protects against the worst effects of Covid-19.
AstraZeneca - which developed the vaccine with Oxford University scientists - said the trial's independent safety monitors found no serious side-effects, including no increased risk of rare blood clots.
Several countries - including Ireland and France - temporarily suspended use of the AstraZeneca vaccine over fears that it increased the risk of a rare blood clot.
AstraZeneca will file an application with the Food and Drug Administration for authorisation to use its vaccine in the US.
US government advisers will publicly debate the evidence before the agency makes a decision.
The Food and Drug Administration and the Centres for Disease Control and Prevention will decide on authorising the vaccine and guidelines for its use after independent advisory committees review the data.