Pharmaceutical giant AstraZeneca on Wednesday revised down the efficacy results of its COVID-19 vaccine in U.S. trials after health officials raised questions over the accuracy of its earlier admission.
In a release on Wednesday, the British-Swedish firm said its candidate vaccine AZD 1222 had an efficacy rate of 76% against symptomatic COVID-19 illness in its late-stage clinical trial.
The new results were a revision of a few percentage points from the 79% efficacy rate it said on Monday when it announced plans to apply for emergency use authorization from the Food and Drug Administration.
On Tuesday, U.S. health officials at the National Institute of Allergy and Infectious Disease said AstraZeneca had included "outdated information" in its efficacy results that "may have provided an incomplete view" of the data.
AstraZeneca admitted later that day to having used data based on "a pre-specific interim analysis" with a cut-off of Feb. 17, stating they would review the information and release new results within 24 hours.
In the report on Wednesday, AstraZeneca said high-level results of its late-stage trial "confirmed vaccine efficacy consistent with the pre-specified interim analysis" it announced earlier in the week.
It also said its vaccine had a 100% efficacy against severe or critical disease and hospitalization and an 85% efficacy against symptomatic COVID-19 in patients over 65 years of age.
The late-stage trial consisted of more than 32,000 volunteers in the United States, Peru and Chile.
Concerns over its data came after the vaccine was temporarily shelved in more than a dozen European nations over concerns of blood clotting after a handful of cases were identified in those who had received the vaccine.
Governments lifted their suspensions days later after the European regulator said the drug was safe and the issues of blood clotting were not associated with the jab.
Mene Pangalos, executive vice president of AstraZeneca's BioPharmaceuticals research and development department, said the company looks forward to filling out its application for emergency use and preparing to "the rollout of millions of doses across America."
"The primary analysis is consistent with our previously released interim analysis and confirms that our COVID-19 vaccine is highly effective in adults, including those 65 years and over," Pangalos said.
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