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Decline in Varicella-Related Ambulatory Visits and Hospitalizations in the United States Since Routine Immunization Against Varicella

Shah, Samir S. MD, MSCE*†‡; Wood, Sarah M. MD*; Luan, Xiquan MS§; Ratner, Adam J. MD, MPH

The Pediatric Infectious Disease Journal: March 2010 - Volume 29 - Issue 3 - p 199-204
doi: 10.1097/INF.0b013e3181bbf2a0
Original Studies
Press Release

Background: Widespread varicella vaccination has led to substantial decreases in varicella-related mortality and hospitalizations. The effect of the vaccine on ambulatory care utilization is poorly defined.

Objective: To determine trends in varicella-related ambulatory care and hospital discharges before and after vaccine licensure.

Design, Setting, and Participants: Estimates of varicella-related ambulatory and hospital discharges were calculated for the pre- (1993–1995) and post- (1996–2004) vaccine licensure periods using the National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, and National Hospital Discharge Survey.

Main Outcome Measure: Ambulatory and hospital discharge rates for varicella.

Results: The rate of varicella-related ambulatory discharges decreased by 66% from 106.6 per 100,000 (95% confidence interval [CI]: 80.5–132.6) in the prelicensure period to 36.4 per 100,000 population (95% CI: 29.3–43.5) in the post-licensure period (P < 0.001). The decrease was significant across all age groups <45 years, with the greatest reduction (98%) occurring among patients 0 to 4 years of age. The incidence of varicella-related hospital discharges decreased by 53% from 30.9 per 100,000 (95% CI: 24.4–37.3) to 14.5 per 100,000 population (95% CI: 12.1–16.8; P < 0.001). This difference was significant among patients <14 years of age. Rates of varicella-related ambulatory discharges decreased significantly for both whites and non-whites in the postlicensure period, but postlicensure ambulatory discharge rates remained higher for non-whites than for whites. Decreases in varicella-related hospital discharges were statistically significant for whites and non-whites. Racial differences in the incidence of varicella-related hospital discharges also persisted following vaccine licensure.

Conclusions: Varicella-related ambulatory visits and hospitalizations have decreased significantly in the period after licensure of the varicella vaccine.


From the *Division of Infectious Diseases, The Children's Hospital of Philadelphia, Philadelphia, PA; †Departments of Pediatrics and Epidemiology and ‡Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia, PA; §Divisions of Biostatistics and Epidemiology, The Children's Hospital of Philadelphia, Philadelphia, PA; and ¶Departments of Pediatrics and Microbiology, Columbia University, New York, NY.

Accepted for publication August 12, 2009.

Supported by the National Institute of Allergy and Infectious Diseases grant (K01 AI73729) and the Robert Wood Johnson Foundation under its Physician Faculty Scholar Program (to S.S.S.). Also received support from the National Institute of Allergy and Infectious Diseases grant (K08 AI065450) (to A.J.R.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Address for correspondence: Samir S. Shah, MD, MSCE, Division of Infectious Diseases, Room 1526, North Campus, 34th St and Civic Center Boulevard, Philadelphia, PA 9104. E-mail:

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© 2010 Lippincott Williams & Wilkins, Inc.