Why focus on Haemophilus influenzae type b?
Haemophilus influenzae type b accounted for most (95%) severe disease due to Haemophilus influenzae infections before the introduction of Hib vaccines. In total, there are 6 types (named a, b, c, d, e and f) of Haemophilus influenzae bacteria based on differences in the capsule surrounding the bacteria, while other Haemophilus influenzae bacteria have lost their capsule. All types of Haemophilus influenzae may cause disease, especially in persons with weakened immune systems. Hib vaccines provide specific protection against Hib disease only. Unencapsulated Haemophilus influenzae often cause ear infections and conjunctivitis.
