LONDON — Oxford University and the pharmaceutical giant AstraZeneca may have only used partial data when the team announced the strong results from a U.S. trial of its coronavirus vaccine, the National Institute of Allergy and Infectious Diseases said Tuesday in a highly unusual advisory.The agency, part of the National Institutes of Health, said that late Monday, it was notified by the Data and Safety Monitoring Board of its concerns “that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data.”On Monday, Oxford and AstraZeneca announced via news releases and interviews that its 32,000-person clinical trials in the United States, Chile and Peru showed that its vaccine was 79% effective in protecting volunteers from symptomatic covid-19, the illness caused by the coronavirus — and that it was 100% effective against severe illness.The 79% efficacy figure in the AstraZeneca trials was higher than earlier clinical trials run by Oxford in Britain, Brazil and South Africa for the same vaccine, which found the shots 62% effective.