Results from a U.S. trial of AstraZeneca's COVID-19 vaccine may have used "outdated information," a U.S. health agency said Tuesday, a day after the company claimed strong efficacy of its vaccine against COVID-19.
The Data and Safety Monitoring Board (DSMB) of the trial was concerned by information released by AstraZeneca on initial data from its COVID-19 vaccine clinical trial, said a statement of the U.S. National Institute of Allergy and Infectious Diseases (NIAID).
"The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data," said the statement.
"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," said the NIAID.
AstraZeneca reported Monday that its COVID-19 vaccine provided strong protection among adults of all ages in the trials conducted in the United States and some South American countries.
The placebo-controlled trial began in August 2020, involving 32,449 adult volunteer participants enrolled across 88 sites in the United States, Chile and Peru.
One participant received a placebo for every two participants who received AZD1222, resulting in approximately 20,000 people receiving the investigational vaccine.
The vaccine was administered as two doses four weeks apart.
AZD1222 demonstrated statistically significant vaccine efficacy of 78.9 percent in preventing symptomatic COVID-19 and 100 percent efficacy in preventing severe or critical disease and hospitalization, according to a statement of the U.S. National Institutes of Health (NIH) on Monday.
In participants 65 years and older, vaccine efficacy against symptomatic COVID-19 was 79.9 percent.
The DSMB conducted a review of blood clots and cerebral venous sinus thrombosis among participants, and found no increased risk of these conditions in vaccinated participants, said the NIH.
At least 20 European countries had fully or partially suspended the use of the AstraZeneca coronavirus vaccine following reports of suspected deaths from blood clots after vaccination, which prompted the European Medicines Agency's investigation and the World Health Organization's safety review.
AstraZeneca has been eyeing filing application to the U.S. Food and Drug Administration (FDA) in April and getting approval for emergency use, even as its vaccine sits at the center of concerns in Europe.
The NIAID said that authorization and guidelines for use of the vaccine in the United States will be determined by the FDA and the U.S. Centers for Disease Control and Prevention after thorough review of the data by independent advisory committees.