Impact of Rotavirus Vaccination On Acute Care Visits, Hospitalizations and Laboratory Testing in Wisconsin, 2002-2008

Background: Rotavirus is a highly communicable virus and the most common cause of severe gastroenteritis among infants and young children in the United States.  In February 2006, a new rotavirus vaccine was licensed, and in August 2006 the Advisory Committee on Immunization Practices recommended its routine use in infants.  Additionally, a second rotavirus vaccine was licensed in April 2008. 

Objectives: To assess the uptake of rotavirus vaccine throughout Wisconsin and determine the statewide impact of rotavirus vaccination on morbidity.

Methods: We analyzed data from four sources: the population-based Wisconsin Immunization Registry, a statewide hospital inpatient surveillance system, a network of outpatient clinics with 2.4 million outpatient visits during 2002-2008, and a statewide network of up to 27 laboratory testing sites. 

Results: By July 1, 2008, 95% of children aged 9-21 months received at least one dose of rotavirus vaccine; 37% received a complete series (3 doses).  Rotavirus-related hospitalizations (ICD-9=008.61) decreased from an annual mean of 419 during 2002-2006 to 66 during January–June 2008 (84% decline).  Acute care visits for all-cause diarrheal illness among children aged less than 12 months decreased by 54% during 2008 compared to 2006.  While the average number of rotavirus tests conducted weekly has remained relatively constant during 2005-2008, the percentage of tests positive for rotavirus decreased by 33%. 

Conclusions: Our study results demonstrate the effective use of large, complimentary sources of data, including an immunization registry, to ascertain statewide impacts on rotavirus-related morbidity and laboratory testing following the introduction of a new vaccine.  The brisk uptake of rotavirus vaccine among Wisconsin’s infants during the first two seasons following licensure was associated with a signficant reduction of rotavirus-related outpatient visits, hospitalizations and laboratory testing.