AstraeZeneca COVID vaccine

FILE - In this file photo dated Sunday, Feb. 7, 2021, a vial of the Oxford-AstraZeneca vaccine against COVID-19 at a hospital in Sofia, Bulgarian. South Africa on Sunday Feb. 7, 2021, has suspended plans to inoculate its front-line health care workers with the AstraZeneca vaccine after a small clinical trial suggested that it isn't effective in preventing mild to moderate illness from the variant dominant in the country.

The independent board that reviews data from multiple COVID-19 vaccine candidates has expressed concern over AstraZeneca's announcements on its latest findings, according to a statement posted early Tuesday by the National Institute of Allergy and Infectious Diseases.

"Late Monday, the Data and Safety Monitoring Board (DSMB) notified NIAID, BARDA, and AstraZeneca that it was concerned by information released by AstraZeneca on initial data from its COVID-19 vaccine clinical trial," the statement says. "The DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.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."

AstraZeneca has not responded to CNN's request for comment.

Early Monday, AstraZeneca issued a press release saying its COVID-19 vaccine showed 79% efficacy against symptomatic disease and 100% efficacy against severe disease and hospitalization, citing long-awaited US trial data. The latter figure was based on five events in the placebo arm, NIAID Director Dr. Anthony Fauci said during a coronavirus briefing Monday.

The DSMB is an independent expert group that sees trial data before the pharmaceutical companies, the doctors running the trials, or even the US Food and Drug Administration. It has the power advise a company of positive interim findings, or to halt a trial over safety concerns. That's what happened to the AstraZeneca trial in September after a study participant developed neurological symptoms, for example.

Last year, the National Institutes of Health appointed a common DSMB to monitor COVID-19 vaccine clinical trials that were being funded by the federal government — including AstraZeneca, Moderna and Johnson & Johnson. This DSMB has 10 to 15 members with specialties including vaccine development, statistics and ethics.

DSMBs sometimes disagree with investigators over the interpretation of trial results, Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said in a statement to the Science Media Centre in the UK. But that's usually done in private, he said, "so this is unprecedented in my opinion."

However, he noted, he isn't concerned unless there's a safety issue, "which does not appear to be the case."

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Jamie Gumbrecht contributed to this report.