Haemophilus influenzae type b vaccine (Hib vaccine or PRP vaccine) is a conjugate vaccine eveloped for the prevention of invasive disease caused by Haemophilus influenzae type b bacteria. The Centers for Disease Control and Prevention (CDC) has made recommendations for the use of the Hib vaccine. Due to routine use of the Hib vaccine in the U.S. from 1980 to 1990, the incidence of invasive Hib disease has decreased from 40-100 per 100,000 children down to 1.3 per 100,000. Vaccinations against Haemophilus influenzae (Hib) have decreased early childhood meningitis significantly in developed countries and recently in developing countries .