Results from a US trial of AstraZeneca's coronavirus vaccine may have used "outdated information," US federal health authorities said on Tuesday.
AstraZeneca's release Monday of encouraging data from its US trial raised hopes that the British-Swedish company could regain public trust after a troubled rollout.
But just hours after the company's announcement, the US Data and Safety Monitoring Board said in an unusual statement that it was concerned AstraZeneca may have provided an incomplete view of the efficacy data.
"Late Monday, the Data and Safety Monitoring Board (DSMB) notified (...) AstraZeneca that it was concerned by information released by AstraZeneca on initial data from its COVID-19 vaccine clinical trial," the statement read.
"The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data. "
"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."
Reacting to the statement, AstraZeneca said Tuesday that the results it released a day earlier included information through February 17 but appeared to be consistent with more up-to-date 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," the company said in a statement.
AstraZeneca promised an update "within 48 hours."
But experts fear the new communication misstep could further harm the reputation of the shot and erode vaccine confidence more broadly.
"I doubt it was (US officials') intention to deliberately undermine trust in the AstraZeneca vaccine, Dr Paul Hunter, a professor of medicine at the University of East Anglia told AP news agency.
"But this will likely cause more vaccine hesitancy.''
Initial report findings
AstraZeneca reported Monday that its COVID-19 vaccine provided strong protection among adults of all ages in a long-anticipated US study.
The finding was seen as a step towards rebuilding public confidence in the shot around the world and getting approval in the US.
According to the study of 30,000 people, the vaccine was 79% effective at preventing symptomatic cases of COVID-19 — including in older adults. There were no severe illnesses or hospitalizations among vaccinated volunteers, compared with five such cases in participants who received dummy shots — a small number, but consistent with findings from Britain and other countries that the vaccine protects against the worst of the disease.
AstraZeneca also said the study’s independent safety monitors found no serious side effects, including no increased risk of rare blood clots like those identified in Europe, a scare that led numerous countries to briefly suspend vaccinations last week.
The company aims to file an application with the Food and Drug Administration in the coming weeks, and the government’s outside advisers will publicly debate the evidence before the agency makes a decision.
Authorisation and guidelines for use of the vaccine in the United States will be determined by the Food and Drug Administration and Centers for Disease Control and Prevention after a thorough review of the data by independent advisory committees.