Anaphylactic reaction following vaccination. Administer w/ caution to patients w/ thrombocytopaenia or bleeding disorder. Syncope (fainting) can occur as psychogenic response to needle inj. Do not administer intravascularly. Ab response in patients w/ endogenous or iatrogenic immunosuppression may be insufficient. Interference w/ serological testing. Not all infants <6 mth of age born to women vaccinated during pregnancy will be protected (passive protection). Safety & efficacy of active immunisation have not been established in infants <6 mth of age.