A medical syringe and vials in front of the AstraZeneca British biopharmaceutical company logo in this illustration photo taken on 18 November 2020.STR | NurPhoto | Getty ImagesU.S. health officials released a bizarre statement early Tuesday that AstraZeneca may have based its Covid-19 vaccine trial results on outdated information.The company’s fumble was just the latest “self-inflicted wound” in a series of missteps that threatens to erode public trust in its shot, experts on public health and vaccines told CNBC.On Monday, AstraZeneca announced the long-awaited results of its phase three clinical trial of the Covid-19 vaccine it developed with the University of Oxford, saying it was 79% effective in preventing symptomatic illness and 100% effective against severe disease and hospitalization. The analysis was based on 32,449 participants across 88 trial centers in the U.S., Peru and Chile, according to the company.Results questionedThe National Institute of Allergy and Infectious Diseases threw the accuracy of those results into question early Tuesday when it said it was informed by the data and safety monitoring board overseeing the trial that the U.K.-based company may have included information in its U.S. vaccine trial results that 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 NIAID said in a statement.NIAID Director Dr. Anthony Fauci said the DSMB, an independent group of experts who oversee U.S. clinical trials, raised concerns with the agency because it felt the results in AstraZeneca’s press release looked more favorable than more recent data from the vaccine study had shown, according to Stat News. “I was sort of stunned,” Fauci told Stat, adding that the agency could not remain silent.Unusual statementThe statement from the NIAID, which is part of the National Institutes of Health, was highly unusual, health experts said. The last time a statement from the U.S. agency caused such a stir was in September when one of its panels said there was “insufficient data” to show convalescent plasma works against the coronavirus, contradicting claims made by then-FDA Commissioner Dr. Stephen Hahn.AstraZeneca’s data hiccup is just the latest example in a series of blunders by the company that could affect people’s willingness to take the vaccine, which may be authorized for use in the U.S. as early as next month, said Isaac Bogoch, an infectious disease expert who has sat on numerous data and safety monitoring boards.The problems first began in September after the company failed to promptly notify Food and Drug Administration officials that it halted its trial globally after a participant in a study fell ill, according to The New York Times. AstraZeneca would later face more issues, including criticism after volunteers in its trials were given incorrect vaccine dosages and countries questioning whether its vaccine was appropriate for use in people over 65. Most recently, countries temporarily suspended use of the shot following reports of blood clots in some vaccinated people.Preventable flaws”This has been an endless roller coaster of what I could call preventable communication flaws,” Bogoch told CNBC. “You’ve got to be open, you’ve got to be honest, you’ve got to be transparent. That includes the good news that also includes the bad news.”Bogoch said the missteps aren’t good for public trust in the vaccine, adding, “We’re already dealing with pubic trust issues in the vaccine rollout [overall] and you have to have a public trust to have a successful public health initiative.”Dr. Leana Wen, a public health professor at George Washington University and a former Baltimore health commissioner, said AstraZeneca’s most recent hiccup could not only damage public trust in the company’s vaccine but trust in all Covid-19 vaccines.”At this point, it is really critical for there to be total transparency. We need to know what happened. Why does there seem to be this discrepancy in data?” Wen said. “I cannot recall seeing public disagreements like this. And that, again, raises red flags at a time where we can least afford it.”‘Rest assured’During an interview Tuesday on CNN, President Joe Biden’s senior advisor on the pandemic, Andy Slavitt, attempted to reassure Americans about the vaccines, saying, “the public should rest assured that nothing will get approved unless the FDA does a thorough analysis of this data.”When AstraZeneca’s vaccine goes through FDA review, the agency “will render a judgment on both what the data says, or what it’s saying, and also whether or not it will be approved. And so until that time, this is all just stuff that will happen in the background,” Slavitt said. “We believe that this transparency and the scientific independence is vital for public trust.”While Americans may not trust the vaccine, the data debacle is unlikely to impact the FDA’s review of the shot once the company submits it for emergency use authorization, said Lawrence Gostin, a law professor and director of the World Health Organization’s Collaborating Center on National and Global Health Law.Pivotal”Though, it certainly doesn’t help to have the NIH rebuke you right before you’re applying for authorization,” Gostin said, adding that the number of “self-inflicted wounds” the company has had is “astounding.” “AstraZeneca has got a good and safe vaccine that I think is going to help vaccinate America and the whole world.”Dr. William Schaffner, an epidemiologist who previously sat on two data safety monitoring boards for staphylococcal vaccines, said FDA’s eventual authorization will be pivotal, not only for the U.S., but for other countries since AstraZeneca’s vaccine is cheaper and easier to distribute that its competitors.”That would resonate around the world and give other ministries of health confidence in this vaccine,” Schaffner said.Correction: This story has been updated to correct the dosing regimen of the AstraZeneca vaccine. It requires two doses.