Patterns of Haemophilus influenzae type b Invasive Disease in New York State, 1987 to 1991: The Role of Vaccination Requirements for Day-Care Attendance

Haemophilus influenzae type b (Hib) is the most common cause of bacterial meningitis in young children and is a major cause of other invasive bacterial disease.1 The case fatality rate for Hib meningitis is 1.0% to 3.4%.2,3 Also, 14% of meningitis cases result in persisting neurologic sequelae and 10% to 11% result in sensorineural hearing loss.4,5 With the introduction of Hib vaccines in 1985, what was once a potentially devastating disease is now preventable by vaccination.6 The risk of Hib in day-care centers (DCCs) is highest for younger children (≤23 months of age), during the first month of enrollment in day care, and for those children who attend larger day-care centers as opposed to home day-care settings.7 The incidence of Hib disease is higher for blacks, Hispanics, native Alaskans, American Indians, and children of lower socioeconomic status.8 Increasing enrollment in licensed DCCs throughout the country has provided an opportunity, through entrance requirements, to ensure that these children receive public health preventive measures such as vaccinations. Most states have laws requiring certain vaccinations before entry into DCCs; however, many states do not have a specific DCC entry requirement for Hib vaccination.9 The purposes of this article are to examine patterns of Hib incidence in New York State by gender, race, and age and to evaluate Hib disease within the DCC setting in New York State in relation to changing Hib vaccine requirements for DCCs. METHODS We conducted a retrospective study of invasive Hib disease in New York State outside New York City.