U.S. health officials raised concerns early Tuesday that positive results that AstraZeneca announced Monday for its Covid-19 vaccine may have been based on “an incomplete view of the efficacy data” from a clinical trial and relied on “outdated information,” throwing another curveball in the saga of the company’s vaccine. In a statement issued soon after midnight Tuesday morning, the National Institute of Allergy and Infectious Diseases said it had been informed about the data questions by the data and safety monitoring board auditing the trial.