Before 1985, Haemophilus influenzae serotype b (Hib) was the most common ca
use of invasive bacterial disease in children less than 5 years of age in t
he United States, causing approximately 12,000 cases of bacterial meningiti
s and 7500 cases of other invasive Hib infections each year.(20) Rates of H
ib were highest among children less than 18 months of age; before 5 years o
f age, one in 200 children developed invasive Hib disease.(20,) (65) The ca
se-fatality rate was 2% to 5%, and 15% to 30% of survivors of meningitis ha
d hearing impairment or other neurologic sequelae.(20) The burden of illnes
s caused by Hib made the development and use of effective Hib vaccines a pu
blic health priority. The use of these vaccines has resulted in the virtual
elimination of Hib invasive disease among infants in only 10 years, which
places this intervention among the most notable public health achievements
of the past decade.(18)