The invention features a novel influenza antibody that specifically binds to influenza hemagglutinin and reduces or inhibits hemagglutinin binding to sialic acid. The invention also provides methods, compositions, and kits featuring the novel antibody and its use in preventing or treating influenza infection.

The present invention relates to stabilized IgG4 antibodies, to methods of producing such antibodies and to uses of such antibodies as a medicament. In a main aspect, the invention relates to a stabilized IgG4 antibody, comprising a heavy chain and a light chain, wherein said heavy chain comprises a human IgG4 constant region having a substitution of the Arg residue at position (409), the Phe residue at position (405) or the Lys residue at position (370).