The Food and Drug Administration has asked AstraZeneca for a large amount of additional data related to its Covid-19 vaccine, a further delay in the company’s application for an emergency authorization or EUA, in the United States, according to a letter from NBC News.
AstraZeneca sent the letter on April 21 to US researchers in clinical trials. It reads in part: “This is a complex presentation that includes data from studies conducted outside the United States, as well as new data from the global release of the vaccine, and significant additional data requests have been received from the FDA.”
Complete coverage of the coronavirus outbreak
AstraZeneca expected to apply to join the EU in late March or early April.
Still, the company says it intends to file documents within the “coming weeks.”
While it’s not uncommon for federal regulators to request additional information from companies seeking an emergency use permit, the FDA probably also wants to see all of AstraZeneca’s data for a rare blood clot called cerebral sinus venous thrombosis associated with the vaccine. abroad. These clots are also associated with the Johnson & Johnson vaccine used in the United States, which resulted in an 11-day break from the vaccine. Both vaccines use the same technology called adenovirus to teach the immune system to fight the virus that causes Covid-19.
“When there are unusual side effects, there may be even more details that the review committee will ask for so they can make a good judgment,” said Dr. Buddy Creech, director of the Vanderbilt Vaccine Research Program. at Vanderbilt University Medical Center in Nashville.
“The FDA is under a lot of pressure to make things right,” Creech added.
As the AstraZeneca vaccine has been used for several months throughout Europe and Asia, there is a significant amount of data that the company needs to collect.
The vaccine is one of several approved by the World Health Organization for use under COVAX, a global initiative working to provide Covid-19 vaccines. The WHO conducted its own safety review and concluded that the benefits of the vaccine outweighed all the risks.
But following reports of blood clots – prompting several countries to stop using the AstraZeneca vaccine and in some cases to stop using it altogether – the FDA’s decision has significant weight.
“What the United States thinks about a product is important,” said John Grabenstein, a former executive director of vaccine medicine at Merck and a former immunologist with the Department of Defense.
Dr William Hartman, chief researcher at the AstraZeneca vaccine testing site at the University of Wisconsin, Madison, said the delays were disappointing for US clinical trial teams, who “made a huge effort” to study the vaccine.
But he supports the FDA’s further efforts. “They search under every stone, making sure it’s the safest product that can be put there,” Hartman said.
Last May, the United States gave AstraZeneca more than $ 1 billion to develop and study the Covid-19 vaccine as part of the Trump administration’s initiative for Operation Warp Speed. Due to this agreement, AstraZeneca is required by contract to apply for EUA in the United States, but even if it is allowed, the vaccine may never be used here.
“We can predict that we will not use the doses of AstraZeneca that we expect to come online,” said Andy Slavitt, an adviser to Covid-19 in the Biden administration during a briefing this week, adding that the United States plans to supply AstraZeneca. which has been purchased in advance in other needy countries.
“We have enough vaccines,” Slavit said, referring to doses from Pfizer-BioNTech, Moderna and Johnson & Johnson.
Failures and wrong steps
Last summer, when the race to develop the Covid-19 vaccine gained momentum, researchers at Oxford University, who developed the vaccine in partnership with AstraZeneca, were the first to report that the shots triggered a significant immune response, producing both antibodies against the virus and T cells that look for infected cells and attack them.
But AstraZeneca soon experienced several failures and wrong steps that contributed to issues related to its data.
In November, the company acknowledged that some of the vials used in clinical trials did not have the correct vaccine concentration, meaning that some volunteers in the UK received half the dose, while others received the full dose. The error led to confusion about the correct way to interpret the findings of efficacy. AstraZeneca blamed the error for a manufacturing problem.
Then in March, the National Institute of Allergy and Infectious Diseases issued an unusual statement late at night stating that AstraZeneca “may have included outdated information” in encouraging results about its U.S. experiments, which the company published just hours earlier. . The company was forced to review and republish its data after the Data and Safety Monitoring Council – a group of independent experts reviewing data on the safety and efficacy of vaccines in the United States – said it was “concerned” about AstraZeneca’s data.
The different results were not that far off – 79 percent effective versus 76 percent effective, but the differences were confusing, Grabenstein said. “What you want to get out of phase 3 is good, clean data,” he said. “You want to show people how you did math.”
Full data from the American trials, such as the one conducted by Hartmann in Wisconsin, have not yet been published.
“This suggests that there is an inadequate amount of safety data,” said a source with in-depth knowledge of Covid-19 vaccines, and AstraZeneca in particular. Asked for comment, an AstraZeneca spokesman cited the company’s previous statement that it planned to apply for the EUA in the coming weeks.
Download the NBC News app to fully cover the coronavirus outbreak
Hartman said he was unable to see the full set of data from studies in the United States, but added that he did not see major safety concerns among nearly 400 people in his study of the AstraZeneca vaccine.
Still, it is clear that AstraZeneca needs to solve significant problems.
If the FDA denies AstraZeneca EUA, it could have a softening effect on the rest of the world. Even if the United States does not need the AstraZeneca vaccine, other countries do.
“If the FDA considers it a safe and effective and good vaccine to be used among the American population,” Hartmann said, “it will definitely help its adoption around the world.”
Follow NBC HEALTH on Twitter and Facebook.