Scientists have developed a nasal spray vaccine that blocks bird flu infection in animals and works even when standard flu shots fall short. By stopping the virus in the nose and lungs, it could reduce both severe disease and transmission. Credit: Shutterstock H5N1 avian influenza, often called bird flu, was first identified in the United States in 2014. Since then, the virus has moved beyond wild birds, spreading into farm animals and eventually infecting people. More than 70 human cases have