In revised estimate, AstraZeneca says vaccine’s efficacy is 76%
In a revised estimate, AstraZeneca said in a news release Thursday that its COVID-19 vaccine candidate demonstrated an overall efficacy of 76% against symptomatic disease in a phase 3 trial conducted mostly in the United States.
The new estimate was from a primary efficacy analysis of the trial, which will form the basis of AstraZeneca’s regulatory submission to the FDA for an emergency use authorization in the coming weeks, the company said.
Source: Adobe Stock
The primary analysis continued to show that the vaccine, AZD1222, was completely protective against severe or critical disease and hospitalization, according to AstraZeneca. The company reported that the vaccine was 85% efficacious against symptomatic COVID-19 in participants aged 65 years or older.
AstraZeneca raised eyebrows earlier this week by releasing an interim analysis that showed the vaccine had an overall efficacy of 79%. In a subsequent letter, the data safety and monitoring board (DSMB) said it was concerned that the drug maker “may have included outdated information” in the press release announcing those interim results, noting that there were available data showing that the vaccine was slightly less efficacious overall.
The DSMB sent the letter to AstraZeneca and federal officials, including National Institute of Allergy and Infectious Diseases Director, Anthony S. Fauci, MD, the White House’s chief medical advisor, who called the decision to release outdated efficacy data “an unforced error.”
AstraZeneca said the initial data released on Monday were from a prespecified interim analysis with a data cutoff of Feb. 17. It said it had already reviewed a preliminary assessment of the primary analysis — the data released Thursday — and that “the results were consistent with the interim analysis.”
The trial was conducted at 88 sites in the U.S., Chile and Peru. The newly released efficacy estimates were based on 190 symptomatic cases of COVID-19 among more than 32,000 trial participants who were randomly assigned in a 2-to-1 ratio to receive the vaccine or a placebo. There are 14 more potential cases under investigation, which could change the efficacy estimate slightly, AstraZeneca said.
The company said all eight cases of severe COVID-19 diagnosed during the trial occurred in the placebo group.
AstraZeneca previously reported that an independent review by the DSMB identified no safety concerns in the new trial, including no increased risk for thrombosis or “events characterized by thrombosis” among more than 21,500 people who had received at least one dose of the vaccine.
The European Medicines Agency recently declared the AstraZeneca shot safe after several European countries halted their rollout of the vaccine over reports of blood clots in vaccinees.
AstraZeneca has not reported data on how the vaccine has performed against SARS-CoV-2 variants, although a company executive said previously that they were encouraged by the results given that the trial took place in areas where variants are circulating.
The vaccine has already been licensed for use in more than 70 countries. If the FDA authorizes its use in the U.S., AstraZeneca has said it will have 30 million doses available right away and another 20 million more soon after that, for a total of 50 million doses in the first month.
As of Wednesday, more than 130 million doses of COVID-19 vaccine had been administered in the U.S. and more than 46 million people were fully vaccinated, according to CDC tracking.
The AstraZeneca vaccine, which uses a chimpanzee adenovirus, can be transported and stored at normal refrigerated temperatures for at least 6 months and administered within existing health care settings without a need for special preparations.
Perspective
Back to Top
The revised data from AstraZeneca still demonstrates that the vaccine is excellent, with an efficacy of 76%, and 100% effective against hospitalization and severe COVID-19. It is unfortunate that there was so much chaos around the reporting of the results. It reiterates the importance of why results by press release can be problematic. It will be important to see the results when they are released for review by the FDA.
Collapse