A serious shortcoming of current influenza virus vaccines is the need to reformulate them every year or two as the virus undergoes antigenic drift. Many virologists have been captivated by the idea of a more universal vaccine that would endure longer, perhaps a decade or more. The identification of a conserved domain in the stalk region of the viral HA protein that gives rise to antibodies that block infection by 10 HA subtypes was a step in this direction. The next phase in the development of a new vaccine, the production of an antigen that confers broader protection, has been achieved using an HA molecule lacking the globular head.
