AstraZeneca might have included outdated information from a clinical trial of its Covid-19 vaccine, a US health agency said on Tuesday, potentially throwing previously published positive results into doubt.
The National Institute of Allergy and Infectious Diseases said it had been notified by the trial’s data and safety monitoring board that “it was concerned by information released by AstraZeneca on initial data from its Covid-19 vaccine clinical trial”.
“The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data,” the NIAID said.
It said the board had also notified the US Biomedical Advanced Research and Development Authority and Anglo-Swedish pharmaceutical company of its concerns.
The NIAID said it had urged AstraZeneca “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”.
AstraZeneca and Oxford university did not immediately respond to a request for comment early on Tuesday.
The statement came after results from a long-awaited American trial of the Oxford/AstraZeneca vaccine were released on Monday. More than 32,000 volunteers took part, mostly in the US, but also in Chile and Peru.
The trial showed the vaccine was 79 per cent effective at stopping symptomatic Covid-19 and 100 per cent effective at preventing people from falling seriously ill.
The company said there were no safety issues regarding blood clots. Earlier reports of side effects from taking the vaccine, including a rare combination of blood clots, bleeding and low platelets, had prompted at least 16 European countries to suspend use of the jab.
Most have now resumed its use, after the European Medicines Agency said it found no link between clotting and the vaccine. The drugs watchdog left the door open to a link between the vaccine and the rarer combination of side effects, but has said throughout the crisis that the vaccine’s benefits far outweigh its risks.