Intussusception incidence relative to rotavirus vaccine use in Honolulu

Abstract

Study objectives: Rotavirus vaccine was in use during August 1998 to October 1999. Epidemics of intussusception during this period were allegedly caused by rotavirus vaccine, which prompted the vaccine to be withdrawn. Hawaii's geographic location between Asia and the mainland United States may subject it to infectious disease epidemic periods midway between occurrence in Asia and occurrence in the mainland United States. In contrast, immunization recommendations are temporally identical across all 50 states. The purpose of this study is to determine whether an epidemic of intussusception was experienced in Honolulu during the period of Rotavirus vaccine use. Methods: This is a retrospective study of data obtained from inpatient and emergency department discharge diagnosis codes of intussusception for children up to 36 months of age. The incidence data were plotted by time periods to identify possible epidemic periods. Results: Among those younger than 36 months old, the incidence of intussusception (in 4-month blocks) during the rotavirus vaccine use period was 4, 4, 2, 4 and 2 cases during each of the 4-month blocks beginning July 1998 and ending December 1999. This compares to an incidence of 2 to 4 cases per 4-month block before the rotavirus vaccine period from May 1994 to June 1998. From January 2000, the incidence per 4-month block has been 4, 4, 6, 6, 5, 4, 6, 4, 5, 4, 4, and 1. This suggests a small epidemic of intussusception cases well after the period of rotavirus vaccine use. Conclusion: These incidence data are inconsistent with the allegation that rotavirus vaccine caused an epidemic of intussusception in Honolulu.