Varicella-related hospitalization and emergency department visit rates, before and after introduction of varicella vaccine, among white and black children in Hamilton County, Ohio.

OBJECTIVE. The American Academy of Pediatrics recommended routine use of varicella vaccine in pediatric practice in 1995. We examined the impact of varicella immunization on population-based rates of pediatric varicella-related hospitalizations and emergency department ( ED) visits in the years before and after introduction of varicella vaccine. STUDY DESIGN. Discharge data for hospitalizations and ED encounters from 1990 through 2003 were queried for patients < 20 years of age with varicella International Classification of Diseases, Ninth Revision, Clinical Modification codes ( 052.0-052.9) in any diagnostic position. Addresses were geocoded for identification of Hamilton County, Ohio, residents. Rates were calculated according to year, age, and race, with census estimates. RESULTS. During the 14-year study period, there were 3983 incident varicella cases; 335 patients were hospitalized and 3833 were treated only in the ED. The rate of varicella-related hospitalizations decreased from 15.7 cases per 100 000 population to 5.5 cases per 100 000 population between the prevaccine period ( 1990 1995) and the postvaccine period ( 1996-2003); varicella-related ED use decreased from 178.2 cases per 100 000 population to 61.2 cases per 100 000 population. In the prevaccine period, hospitalization and ED visit rates were significantly higher for black children than for white children. In the postvaccine period, hospitalization rates did not differ according to race but ED visit rates remained significantly higher for black children, compared with white children. CONCLUSIONS. Varicella-related hospitalization and ED visit rates decreased significantly for both white and black children in Hamilton County, Ohio, after the introduction of varicella vaccine, and the racial disparity found before licensure decreased after licensure.