Learning from the 2009 H1N1 pandemic: prospects for more broadly effective influenza vaccines.

Calls to develop a universal influenza vaccine have increased in the wake of the 2009 H1N1 influenza pandemic. This demand comes at a time when analyses of the human antibody repertoire, informed by structures of complexes between broadly neutralizing antibodies and influenza hemagglutinin, have revealed the target of a class of broadly neutralizing antibodies. Recent studies suggest a path forward to more broadly protective influenza vaccines.