March 23, 2021
U.S. health officials are questioning the results of AstraZeneca's COVID-19 vaccine trial, suggesting that findings released Monday by the pharmaceutical company may provide "an incomplete view" of the vaccine's effectiveness.
The Data and Safety Monitoring Board is concerned that AstraZeneca may have included "outdated information" in the data, according to a statement issued early Tuesday morning by the National Institute of Allergy and Infectious Disease.
The NIAID urged AstraZeneca to work with the board to review its efficacy data and ensure that the most accurate information would be made public as soon as possible.
AstraZeneca said the data published Monday was based on an interim analysis with a pre-specified cut off date of Feb. 17. The company pledged to issue the results of its primary analysis within 48 hours.
"We have reviewed the preliminary assessment of the primary analysis and the results were consistent with the interim analysis," the company said in a statement. "We are now completing the validation of the statistical analysis. We will immediately engage with the independent data safety board to share our primary analysis with the most up to date efficacy data."
The preliminary findings found the two-dose vaccine to be 79% effective at preventing symptomatic infections and 100% effective against severe complications and hospitalizations. It also found the vaccine to be 80% effective among seniors ages 65 and older.
The study involved more than 30,000 people. Two-thirds of them received the vaccine. The others received a placebo.
No safety concerns were reported. There was no increased risk of blood clots or thrombotic events among the participants who received at least one dose.
Earlier this month, several countries suspended the vaccine's use after a few people developed blood clots after being inoculated. An emergency investigation by European regulators found the vaccine to be "safe and effective" and "not associated" with the blood clots. Regulators have urged countries to continue administering the vaccine.
AstraZeneca plans to submit its vaccine to the U.S. Food and Drug Administration for an emergency use authorization in the coming weeks. Independent advisory committees will be tasked with reviewing the company's clinical trial data.
If authorized, the U.S. Centers for Disease Control and Prevention would issue guidelines dictating the way the vaccine should be utilized.
Dr. Anthony Fauci, the nation's leading infectious disease expert, said Monday that the results from AstraZeneca's clinical trials were "good news."
"There are very many countries in Europe and throughout the world who have already authorized this," Fauci said at a White House press briefing. "So the fact that a United States-run study has confirmed the efficacy and the safety of this vaccine I think is an important contribution to global health in general."
Fauci, who serves as President Joe Biden's chief medical advisor, also expressed confidence in the FDA's process of granting emergency use authorizations.
"The FDA is going to very, very carefully go over all of these data," Fauci said. "There will be an application for an EUA, and I can tell you, you can rest assured that the FDA will put a great deal of scrutiny in every aspect of these data."
Previous clinical trials have found AstraZeneca's vaccine to be more effective against COVID-19 when the two doses are administered over an extended interval of up to 12 weeks instead of four weeks. This timeline would allow for more people to receive their first COVID-19 shots sooner.
Research also suggests the vaccine has the ability to reduce transmission of the coronavirus.
The vaccine, which was developed alongside the University of Oxford, can be stored at normal refrigerated conditions for at least six months and administered without needing to be prepared within an existing health care setting.
If authorized, AstraZeneca's vaccine would become the fourth coronavirus shot available in the U.S., joining vaccines made by Pfizer, Moderna and Johnson & Johnson. The U.S. has agreed to buy 300 million doses of AstraZeneca's vaccine if it is authorized.