AstraZeneca said Wednesday that results from a primary analysis of U.S. trial data show its vaccine is 76 percent effective against symptomatic Covid-19.
Earlier this week, the company announced an efficacy rate of 79 percent after an interim analysis.
Federal health officials questioned the higher rate, saying that AstraZeneca may have included “outdated information.” AstraZeneca responded to the criticism by saying that it was working on more up-to-date information and that the more recent findings are consistent with its initial announcement that the vaccine offered strong protection.
In announcing the 76 percent efficacy rate on Wednesday, AstraZeneca again said that the vaccine it developed along with Oxford University is 100 percent effective in preventing severe and fatal cases.
AstraZeneca said in Wednesday’s statement that the 76 percent rate comes from results of the primary analysis of the U.S. Phase 3 trial and is consistent with the “pre-specified interim analysis” that was announced Monday.
AstraZeneca has said it will now apply to the Food and Drug Administration for emergency use authorization and release its data for analysis by the scientific community in peer-reviewed literature.
More than 50 countries across the world have approved the AstraZeneca vaccine.
The new data from AstraZeneca comes a day after the National Institute of Allergy and Infectious Diseases raised concerns about the information released by the company Monday.
The agency said early Tuesday that the Data and Safety Monitoring Board “expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.”
The institute urged AstraZeneca to work with that board to ensure the most accurate, up-to-date data be made available as quickly as possible.
AstraZeneca said tthe trial results released Monday were based on data with a cut-off point of Feb. 17.
The numbers of symptomatic cases in the trial did change between the two statements.
There were 190 symptomatic cases, which is an additional 49 cases from the interim analysis, the company said Wednesday.
There are 14 other cases that are possible or probable, so the number could fluctuate, it said.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, called the situation unfortunate and an “unforced error.”
“The fact is, this is very likely a very good vaccine,” Fauci said on ABC’s “Good Morning America” Tuesday.
“It was not necessary,” he said. “If you look at it, the data really are quite good. But when they put it into the press release it wasn’t completely accurate.”
The FDA will ultimately make the decision on whether to grant emergency use authorization, and health officials say that will only be done after an independent and thorough review.
If authorized for use, it would be the fourth given the green light in the U.S.
A vaccine developed by Pfizer and BioNTech was the first to be granted FDA authorization, which occurred in December. Since then, vaccines by Moderna and Johnson & Johnson have been granted emergency use authorization.
Phil Helsel is a reporter for NBC News.