AstraZeneca trial results may have included 'outdated' information, U.S. health officials say

Results from a U.S. trial of AstraZeneca's COVID-19 vaccine may have included "outdated information" and that could mean the company provided an incomplete view of efficacy data, U.S. federal health officials said early Tuesday.

Swedish-British pharma company expected to provide an update within 48 hours after rebuke

The U.S. National Institute of Allergy and Infectious Diseases says the Data and Safety Monitoring Board expressed concern that AstraZeneca 'may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.' (Christof Stache/AFP/Getty Images)

Results from a U.S. trial of AstraZeneca's COVID-19 vaccine may have included "outdated information" and that could mean the company provided an incomplete view of efficacy data, U.S. federal health officials said early Tuesday.

AstraZeneca said in a statement that the data it released Monday included cases up to Feb. 17 — as the study rules specified — and that it was continuing to analyze cases that have occurred since then. The company said that a preliminary analysis of data that has continued to roll in was consistent with what it had already reported.

"We will immediately engage with the independent data safety monitoring board [DSMB]," AstraZeneca said. "We intend to issue results of the primary analysis within 48 hours."

AstraZeneca reported Monday that its COVID-19 vaccine provided strong protection among adults of all ages in a long-anticipated U.S. study, a finding that some experts hoped would help rebuild public confidence in the shot around the world and move it a step closer to clearance in the U.S.

In the study of more than 30,000 people, the company reported that the vaccine was found to be 79 per cent effective at preventing symptomatic cases of COVID-19 — including in older adults.

There were no severe illnesses or hospitalizations among vaccinated volunteers, compared with five such cases in participants who received dummy shots — a small number, but consistent with findings from Britain and other countries that the vaccine protects against the worst of the disease.

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Infectious disease specialist Dr. Sumon Chakrabarti explains what the different efficacy rates for the COVID-19 vaccines mean.

AstraZeneca also said the study's independent safety monitors found no serious side effects, including no increased risk of rare blood clots like those identified in Europe, a scare that led numerous countries to briefly suspend vaccinations last week.

Dr. Isaac Bogoch said it was the latest cloud for the company whose vaccine has been approved in dozens of countries, including Canada, but has faced questions over messaging over dose regimens in its trials, its efficacy with seniors, and, most recently, potential side effects for those who've suffered from blood clots.

"This is just a never ending series of public relations nightmares for a company that is producing a vaccine that is supposed to be the vaccine for planet Earth," said Bogoch, an infectious disease physician in Toronto and member of Ontario's COVID-19 Vaccine Distribution Task Force, in an interview with CBC News Network. "This is supposed to be used in many, many parts of the world including low- and middle-income countries,"

Bogoch said it was important to wait for further information from AstraZeneca, and that the next 48 hours would likely see clarifications from the British-Swedish pharmaceutical company and the U.S. regulators.

"Based on the snippets of information that we have now, and that we've seen in the past, this will probably end up being a very good vaccine," he said.

'An unforced error'

But just hours after the encouraging results were reported, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) issued an unusual statement.

The agency said the Data and Safety Monitoring Board (DSMB) "expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data."

"We urge the company to work with the DSMB to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible," the statement went on.

Dr. Anthony Fauci, U.S. President Joe Biden's chief medical adviser, said the DMSB noticing a discrepancy in the data was an example of safeguards in the vaccine approval process being employed, but he characterized the correspondence to AstraZeneca as a "rather harsh note."

"It really is unfortunate this happened," Fauci said Tuesday morning on Good Morning America. "This is what you call an unforced error. The fact is, this is very likely a very good vaccine."

Fauci, the director of NIAID, said he hoped the setback would not contribute to vaccine hesitancy.

WATCH | U.S. safety board raises concern about new AstraZeneca vaccine data:

U.S. health safety board raises concern about latest AstraZeneca vaccine data

3 years ago
Duration 3:38
A day after AstraZeneca released new information about the efficacy of its COVID-19 vaccine, a U.S. health safety board raised concerns about the data the company used.

In the AstraZeneca study, just like studies of the other vaccines in use, some participants get the real vaccine and the rest get dummy shots, and neither they nor their doctors know which is which. Only the DSMB has the power to unlock the code of who got which and peek at how the volunteers are faring before a study is finished.

The DSMB watches for safety concerns and also deems when the study has met pre-determined endpoints showing it's time for an effectiveness calculation. It was the NIH-appointed DSMB that raised the concerns about AstraZeneca's data.

AstraZeneca aims to file an application with the U.S. Food and Drug Administration (FDA) in the coming weeks, and the government's outside advisers will then publicly debate the evidence.

Authorization and guidelines for use of the vaccine in the United States will be determined by the FDA and Centers for Disease Control and Prevention after thorough review of the data by independent advisory committees.

The FDA had set an efficacy threshold of 50 per cent for first-generation COVID-19 vaccines in order to consider authorizing them for use in a pandemic that has now killed over 520,000 Americans. But that was before coronavirus variants began to widely circulate throughout the world, including in the U.S., beginning late in 2020.

Variants first identified in the U.K. (B117), South Africa (B1351) and Brazil (P1) are concerning to health officials who say they could prove more resistant to the current vaccines.

With files from CBC News

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