Before the Hib vaccine became available, this disease was the most common cause of bacterial meningitis in infants and children in the United States. Before the vaccine was developed, there were approximately 20,000 invasive Hib cases annually. Approximately two-thirds of the 20,000 cases were the result of meningitis, and one-third was other life-threatening invasive Hib diseases, such as bacteria in the blood, pneumonia, or inflammation of the epiglottis.
About 1 out of every 200 U.S. children under five years of age got an invasive Hib disease. Hib-related meningitis once killed 600 children each year and left many survivors with deafness, seizures, or mental retardation.
Since the introduction of the conjugate Hib vaccine in December 1987, the incidence of disease has declined by 99 percent. From 1994 to 1998, fewer than 10 fatal cases of invasive Hib disease were reported each year.
This preventable disease was a common, devastating illness as recently as 1990; now, most pediatricians just finishing training have never seen a case. If we were to stop immunization, we would likely soon return to the pre-vaccine numbers of invasive Hib disease cases and deaths.