A U.S. health agency said Tuesday that Oxford-AstraZeneca may have included “outdated information” in trial results of its COVID-19 vaccine, potentially casting doubt over reported efficacy rates.

The announcement comes a day after trial results were released showing a 79% effectiveness with the vaccine.  This will likely question whether AstraZeneca can seek U.S. clearance for the vaccine next month as planned.

The Data Safety Monitoring Board “expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data,” the U.S. National Institute of Allergy and Infectious Diseases said in a statement.

“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 it was notified of the concerns late Monday, along with AstraZeneca and the Biomedical Advanced Research and Development Authority. Led by White House chief medical advisor Dr. Anthony Fauci, the NIAID is part of the National Institutes of Health.

Fauci told ABC News’ “Good Morning America” on Tuesday that the Oxford-AstraZeneca shot is “likely a very good vaccine.” However, he added, the DSMB became concerned that the data in AstraZeneca’s public statement “were somewhat outdated and might, in fact, be misleading a bit.”

In response, AstraZeneca said that the trial published Monday “were based on a pre-specified interim analysis with a data cut-off of 17 February.”

“We will immediately engage with the independent data safety monitoring board (DSMB) to share our primary analysis with the most up to date efficacy data. We intend to issue results of the primary analysis within 48 hours,” the company said in a statement.

The vaccine was suspended worldwide due to a widespread concern with blood clots. However, the findings have been “surprisingly positive” and “good news for the global community.” AstraZeneca has tried to rebuild public confidence since the safety concerns with use if the vaccine

Data from the trial was based on more than 32,000 volunteers across 88 trial centers in the U.S., Peru and Chile.