WASHINGTON (Reuters) - Another 1 million doses of a nasal spray influenza vaccine will be available in the United States this year, Bush administration officials said on Thursday as they sought to calm concerns about a flu shot shortage. The spray vaccine, called FluMist and made by Gaithersburg, Maryland-based MedImmune Inc., is approved only for healthy people aged 5 to 49. It is not intended for the elderly, very young children and others at high risk of serious flu complications. The United States will have enough vaccine and antiviral medicines "to cope with this year's flu season, even if it...