On Monday morning, the drugmaker AstraZeneca released some pretty impressive figures from a U.S. trial that showed its coronavirus vaccine prevents all severe disease from COVID-19. But federal health officials released a rare statement early Tuesday that appears to cast some doubt on those encouraging results. In a statement after midnight, the U.S. National Institute of Allergy and Infectious Diseases—which is headed by Dr. Anthony Fauci—said the independent committee that’s overseeing the trial has “expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.” It didn’t elaborate on exactly what data could be outdated, or how that data could have skewed the results. On Tuesday’s Good Morning America, Fauci expressed his disappointment about what he called an “unforced error” from AstraZeneca, adding: “This is very likely a very good vaccine and this kind of thing does... nothing but really cast some doubt about the vaccines and maybe contribute to the hesitancy.” AstraZeneca is yet to comment on the statement.