AstraZeneca falls after independent data monitor questions potential use of 'outdated' data for vaccine trial

• AstraZeneca shares fell nearly 4% on Tuesday after US health officials raised questions about vaccine trial data.
• A US safety monitoring panel expressed concern the drugmaker used 'outdated' information in an update about a vaccine trial.
• AstraZeneca said it will issue results of the primary analysis "within 48 hours".
  

AstraZeneca shares fell Tuesday after US health officials raised questions about the drug maker's COVID-19 vaccine, saying the company may have used some outdated trial data in its update about the formula.

The Data and Safety Monitoring Board, an independent expert panel that monitors trial safety, said in a statement early Tuesday it was concerned that information released by AstraZeneca about its COVID-19 vaccine clinical trial "may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data."

"We urge the company to work with the DSMB to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible," the safety panel said in a late Monday letter to the National Institute of Allergy and Infectious Diseases, or NIAID, the US Biomedical Advanced Research and Development Authority, or BARDA, and AstraZeneca.

Shares of AstraZeneca fell 3.8% to $49.27 during Tuesday's session.

AstraZeneca said Monday the vaccine it co-developed with Oxford University was 79% effective at protecting against the coronavirus in the vaccine's largest trial yet. It also said the formula was 100% effective at preventing severe COVID-19 and hospitalization. AstraZeneca was to submit the trial data to the US Food and Drug Administration, which has granted emergency use authorization for other COVID-19 vaccines.

AstraZeneca responded to the safety panel on Tuesday, saying the figures it published Monday were based on a pre-specified interim analysis with a February 17 cut-off date for data.

"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," it said in a press release.

The company said it will "immediately engage" with the safety monitoring board to share its primary analysis "with the most up to date efficacy data," with plans to issue results of the primary analysis within 48 hours.