US health officials question results from AstraZeneca’s Covid-19 vaccine trial hours after they’re released

AstraZeneca said a day earlier that its Covid-19 vaccine developed with Oxford University was 79% effective in preventing symptomatic illness

Federal health officials said early on Tuesday that results from a US trial of AstraZeneca’s Covid-19 vaccine may have relied on “outdated information” that “may have provided an incomplete view of the efficacy data,” casting doubt on an announcement Monday that had been seen as good news for the company as well as the global vaccination drive.

In a highly unusual statement released after midnight, the National Institute of Allergy and Infectious Diseases said that the data and safety monitoring board, an independent panel of medical experts under the National Institutes of Health that has been helping to oversee AstraZeneca’s U.S. trial, had notified government agencies and AstraZeneca late Monday that it was “concerned” by information the drugmaker had released that morning.

The institute urged AstraZeneca to work with the monitoring board “to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible.”

Also read: AstraZeneca US trial data shows Covid-19 vaccine 79% effective, safe

In a news release Monday announcing the results of the US trial, AstraZeneca said that the vaccine it developed with the University of Oxford was 79% effective against Covid-19, higher than observed in previous trials, and completely prevented the worst outcomes from the disease. The long-anticipated results were seen as encouraging global confidence in the vaccine, which was shaken this month when more than a dozen countries, mostly in Europe, temporarily suspended the shot’s use over concerns about possible rare side effects.

In recent days, the monitoring board’s analysis was delayed several times because the board had to ask AstraZeneca for revised reports from those handling trial data on behalf of the company, according to a person familiar with the matter who was not authorized to discuss it publicly.

The monitoring board ultimately conveyed the results of the study to AstraZeneca in a meeting over the weekend, leading to the company’s announcement Monday morning.

Asked about the issues with data submission to the monitoring board, an AstraZeneca spokesperson, whom AstraZeneca declined to name, said Friday that it was “completely incorrect” that the trial data had formatting problems or had not been submitted to the study monitor in a clean fashion.

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“As is often the case,” the spokesperson said, monitoring boards “can request new or clarifying analyses of data from the trial. This would enable them to ensure the robustness of their determinations.”

AstraZeneca did not immediately return a request for comment early Tuesday.

Dr. Eric Topol, a clinical trials expert at Scripps Research in San Diego, said it was “highly irregular” to see such a public display of friction between a monitoring board and a study sponsor, which are typically in close concordance.

“I’ve never seen anything like this,” he said in an interview after the institute’s statement was released. “It’s so, so troubling.”

AstraZeneca’s U.S. trial, which involved more than 32,000 participants, was the largest test of its kind for the shot. Although no clinical trial is large enough to rule out extremely rare side effects, AstraZeneca reported that its study turned up no serious safety issues.

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The fresh data may have arrived too late to make much difference in the United States, where the vaccine is not yet authorized and is unlikely to become available before May. By then, federal officials predict, there will be enough vaccine doses for all of the nation’s adults from the three vaccines that have already been authorized: Pfizer-BioNTech, Moderna and Johnson & Johnson.

Even so, the better-than-expected results were seen as a heartening turn for AstraZeneca’s shot, whose low cost and simple storage requirements have made it a vital piece of the drive to vaccinate the world.

The results were also thought to ease concerns about the AstraZeneca vaccine in Europe. In an effort to increase public confidence, many European political leaders have gotten the injections in recent days.

Regulators in Europe initiated a safety review of AstraZeneca’s vaccine earlier this month after a small number of people who had recently been inoculated developed blood clots and abnormal bleeding. The trial did not turn up any sign of such problems, although some safety issues can only be detected in the real world, once a drug or vaccine has been given to millions of people.

AstraZeneca said Monday that it would continue to analyze the new data and prepare to apply in the coming weeks for emergency authorization from the Food and Drug Administration. The vaccine has already been approved in more than 70 countries, but clearance from American regulators would bolster its global reputation.