Results of AstraZeneca’s key trial in the United States on its COVID-19 vaccine, published by press release Monday morning exceeded the expectations of experts. But less than a day later, U.S. health officials questioned the results, which still have not been released in full.
In one test involving more than 32,000 volunteers, about two-thirds of whom have received the vaccine, the injections are 79% effective in preventing symptomatic COVID-19, the company said. This was based on 141 cases of the disease occurring in the vaccine and placebo arms of the trial. There were no cases of serious illness requiring hospitalization among those vaccinated, versus five in the placebo armNational Institute of Allergy and Infectious Diseases (NIAID) chief Anthony Fauci said at a White House press conference on Monday.
“The good news is also that there was comparable effectiveness across ethnicity and age,” Fauci said.
But early Tuesday morning, NIAID issued a very unusual statement questioning the company’s report on its results. The company “may have included outdated information from this trial,” the release said, “which may have provided an incomplete view of the efficacy data.”
The statement said that on Monday evening, the Data Safety Monitoring Board, the independent group of medical experts overseeing the US trial of AstraZeneca, notified NIAID and other health officials that it was “concerned. By the way the results were presented.
On Tuesday morning, AstraZeneca responded to concerns raised by the independent panel of experts. “Numbers published yesterday were based on a pre-specified interim analysis with a deadline for data of February 17, ”the company wrote. “We reviewed the preliminary assessment of the primary analysis and the results were consistent with the interim analysis. We now complete the validation of the statistical analysis. “
The company has vowed to “engage immediately” with the independent panel to “share our core analysis with the most up-to-date efficacy data,” saying it will release results within the next two days.
“As a member of the FDA advisory board, I want to see all the data – all the data that has been collected. Any experience with this. Whatever is relevant to the decision, ”said Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia, who sits on the FDA’s vaccine advisory committee. “Because the most important thing we consider with these vaccines is safety. Safety, security, security. “
Appearing on Hello america On Tuesday, Fauci said the DSMB wrote a “rather harsh note” to AstraZeneca, copying Fauci, saying he felt the data in the press release “might actually be a little misleading.”
“It’s such a shame that this has happened,” Fauci said. “This is really what you call an unforced error, because the point is, it is quite possibly a very good vaccine.”
Other experts have expressed similar concerns over the way the company has presented its data.
“It’s a good vaccine, but that kind of PR stuff just makes it a little more complicated and complicated. It is more difficult for the public to analyze what is going on. We just want a process that is clear and simple, easy to interpret, ”Natalie Dean, biostatistician at the University of Florida, told BuzzFeed News. “We don’t really have any details. But the mere appearance of it all does no one any favors.
The NIAID statement caught many scientists off guard.
“We are in uncharted territory. DSMBs don’t normally do things like this,
and the prohibition on a federal agency issuing a statement raising concerns
about a high profile corporate trial is definitely very, very high, ”John Moore, a virologist at Weill Cornell Medical College in New York City, told BuzzFeed News via email.
The statement by U.S. health officials is just the latest in a series of issues that trials of the AstraZeneca COVID-19 vaccine have faced.
Earlier results from trials in the UK and Brazil – led by the University of Oxford, which developed the vaccine – had indicated an overall efficacy of around 70%. But scientists criticized these trials, which included a range of experimental subgroups with patients of different age groups, doses and intervals between the two injections of the vaccine, making it very difficult to interpret the numbers.
It also meant that the Oxford team had not been able to gather enough data to answer a key question: Does the vaccine protect older people most vulnerable to COVID-19 from getting sick? This has led some countries, including initially Germany, to delay vaccine authorization for use in older groups.
The new trial finally has enough data to answer that question, according to the company’s statement. Analysis of the results in people aged 65 and over indicated an 80% effectiveness in preventing symptomatic COVID-19.
“These results confirm previous results seen in the AZD1222 trials on all adult populations, but it is exciting to see similar efficacy results in people over 65 for the first time,” Ann Halsey of the Faculty of Medicine from the University of Rochester, which co-led the trial for AstraZeneca, said in the company’s statement.
Importantly, the new trial, conducted in the United States and several other countries, is a much simpler design than those led by the Oxford team, with only two experimental groups. The volunteers received either two doses of the vaccine four weeks apart or two injections of saline as a placebo control.
Moore, who has been a leading critic of the Oxford trials, described the US trial to BuzzFeed News last week as a “rigid protocol” that should produce results that are easier to assess.
The company has yet to release data beyond the results summarized in its press release, but said an article “will be submitted for publication in a peer-reviewed journal.” The results will also be submitted as a centerpiece of AstraZeneca’s request to the FDA for the vaccine to be cleared for emergency use in the United States.
“We are preparing to submit these results to the US Food and Drug Administration and roll out millions of doses across America if the vaccine receives US emergency use clearance,” Mene Pangalos said. , AstraZeneca’s executive vice president for biopharmaceuticals, in Monday’s statement. .
These results suggest that AstraZeneca’s two-dose vaccine is somewhat more effective at preventing COVID-19 than the single-injection vaccine made by Johnson & Johnson, which was 66% efficient in the prevention of the disease in its major trial. Both appear to be less effective than the two-dose vaccines manufactured by Pfizer / BioNTech and Moderna, which were over 90% effective. All four vaccines appear to offer very strong protection against severe COVID-19.
The new trial results follow a safety alert for the AstraZeneca vaccine last week, when many European countries temporarily withdrew the vaccine from its use after reports of rare but serious blood clots.
The European Medicines Agency then analyzed data from nearly 20 million people who received the vaccine, finding 18 cases of cerebral venous sinus thrombosis (CVST), which can stop blood from flowing from the brain and cause bleeding, and seven cases of disseminated intravascular coagulation (DIC), which causes clots in tiny blood vessels all over the body. While the agency was unable to rule out a link to the vaccine, it said the vaccine’s benefits in preventing COVID-19 far exceeded the risk of these serious but very rare conditions, and recommended the resumption of vaccination.
AstraZeneca said it found no cases of CVST in its lawsuit. This was expected because the disease is very rare and only about 21,000 people received the vaccine as part of the trial.
Even before Tuesday’s statement by U.S. health officials, some experts feared the vaccine’s troubled history would make it less appealing to the U.S. public than alternatives already available.
“The FDA now has to make a decision, but even if this vaccine is approved, it might be difficult to persuade the public to take it,” Moore told BuzzFeed News Monday. “Perception can come true in situations like this, and the public’s trust just isn’t there now.”
Last week the Biden administration announced that it would lend millions of prefabricated doses of the AstraZeneca vaccine to Canada and Mexico, where it has already been approved.
Dan Vergano contributed reporting for this story.
