This invention relates to prevention and treatment of diseases caused by group A streptococci. More particularly, this invention relates to an antibodies or antibody fragments for treating or preventing group A streptococcus-associated toxic shock syndrome.

Provided herein are methods of immunizing against, treating or preventing streptococcal toxic shock syndrome in a subject, by administration of a group Astreptococcus M protein, inclusive of fragments, variants or derivatives thereof, or an antibody that binds, or is raised against the M protein and optionally a group A streptococcus superantigen protein, inclusive of fragments, variants or derivatives thereof, or an antibody or antibody fragment that binds, or is raised against, the superantigen protein.