British-Swedish drug maker AstraZeneca may have provided incomplete efficacy data on its Covid-19 vaccine from a large-scale US trial, a US health research agency said on Tuesday.
AstraZeneca had said a day earlier that its Covid-19 vaccine, developed with Oxford University in Britain, had been 79 per cent effective in preventing symptomatic illness in a large trial in the US, Chile and Peru.
However, the US National Institute of Allergy and Infectious Diseases (NIAID) reported concerns expressed by the independent Data Safety Monitoring Board (DSMB).
"The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data," the NIAID said.
"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 request cast doubts over the company's plan to seek US emergency use authorisation for the vaccine in the coming weeks.
Authorisation and guidelines for use of the vaccine in the US will be determined by the Food and Drug Administration and Centres for Disease Control and Prevention, after thorough review of the data by independent advisory committees, said the NIAID, which is part of the National Institutes of Health agency.
Hailed as a milestone in the fight against the Covid-19 pandemic when it emerged last year, the AstraZeneca vaccine has faced doubts over its efficacy, dosing regimen and possible side effects.
Its use was temporarily suspended in a number of countries – including a dozen in Europe – over concerns linking it to blood clots.
The European Medicines Agency drugs regulator said the AstraZeneca vaccine is "safe and effective".
