this vaccine is to prevent disease caused by the haemophilus influenzae type b (hib) bacteria. The h. Influenzae (h. Flu) bacteria can cause a range of serious diseases including meningitis with potential brain damage and epiglottitis with airway obstruction poisoning. The hib vaccine is usually given at 2, 4 and 6 months of age. A final booster is given at 12-15 months of age. Hib vaccine rarely causes severe reactions.