Haemophilus influenza type B (known by the initials HiB) is responsible for many infections in children, and prior to the vaccine, caused over half the cases of meningitis in children below age five. Between 5% and 10% of all children who develop HiB meningitis will die, and those who survive may have lasting damage to the nervous system. HiB also causes epiglottitis, and infection that can cause death if not treated immediately. Serious HiB diseases are contagious; so one sick child can expose other children to HiB. The vaccine is not a guarantee that HiB disease cannot occur, but it dramatically reduces the probability of illness. Side effects are rare and minor, consisting of a low grade fever or local reaction at the injection site. The HiB immunization is given in three successive shots in the first six months. A booster dose of the vaccine is given at fifteen months.