Varicella-Related Hospitalizations in the United States, 2000–2006: The 1-Dose Varicella Vaccination Era

OBJECTIVE: To describe the effect of the mature 1-dose varicella vaccination program on varicella morbidity, we analyzed 2 national databases for varicella-related hospitalizations in the United States since implementation of the varicella vaccination program in 1995. PATIENTS AND METHODS: Data from the National Hospital Discharge Survey and Nationwide Inpatient Sample were analyzed to describe trends in varicella-related hospitalizations during the 1-dose vaccination era (2000-2006) compared with those in the prevaccination era (1988-1995). Varicella-related hospitalizations were defined by using International Classification of Diseases, Ninth Revision codes. Results were extrapolated to represent national estimates. RESULTS: Using National Hospital Discharge Survey data, 24,488 varicella-related hospitalizations were estimated to occur in the United States during the 1-dose vaccination era. The varicella-related hospitalization rate was 0.12 per 10,000 population during the 1-dose vaccination era versus 0.42 per 10,000 population in the prevaccination era (P < .01). During the 1-dose vaccination era, the estimated annual average number of varicella-related hospitalizations was significantly lower and decreased by ≥ 65% in all age groups compared with those in the prevaccination era (P < .001 in all age groups). The varicella-related hospitalization rate during the 1-dose vaccination era estimated from the Nationwide Inpatient Sample was 0.09 per 10,000 population. CONCLUSIONS: Varicella-related hospitalization numbers and rates declined significantly during the 1-dose varicella vaccination era. Assuming declines in varicella-related hospitalizations are due, mainly, to the routine childhood varicella vaccination program, these data suggest that varicella vaccination prevented ∼ 50,000 varicella-related hospitalizations in the United States from 2000 to 2006.