Monitoring of Intussusception after RotaTeq Vaccination
Each year in the United States, rotavirus is responsible for more than 400,000 doctor visits, more than 200,000 emergency department visits, 55,000 to 70,000 hospitalizations, and between 20 and 60 deaths among children less than 5 years of age. In 2006, FDA licensed RotaTeq, a new rotavirus vaccine. CDC's Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination of U.S. infants with three doses of RotaTeq given orally at ages 2, 4, and 6 months.
CDC and the Food and Drug Administration (FDA) conduct routine safety monitoring for new vaccines. In 2006, CDC implemented a post-licensure vaccine safety study of the RotaTeq vaccine. Because the previous rotavirus vaccine was withdrawn from the U.S. market due to an association with intussusception (a type of bowel obstruction), this study looked for evidence of a possible link between RotaTeq and intussusception.
VAERS Reports Related to RotaTeq and Intussusception February 1, 2006 through September 25, 2007
VAERS received 1,901 reports of adverse events after RotaTeq vaccination between February 1, 2006 and September 25, 2007; a total of 160 intussusception reports were confirmed.Observed Versus Expected Calculations
Scientist observed in VAERS data 47 intussusception cases (29%) occurred during the first 21 days after vaccination, including 27 intussusception cases (17%) during the first 7 days after vaccination. From VSD data, the expected number of intussusception reports was 151 cases during the first 21 days after vaccination, including 50 cases during the first 7 days after vaccination.
Please note: In comparison to the previous rotavirus vaccine, more than 60% of the intussusception cases occurred between 1 and 7 days after vaccination.
Based on scientific assumptions from the actual vaccine doses distributed, estimated 75% of the intussusception cases that occurred during these time periods were reported to VAERS and that 75% of the vaccine doses distributed were administered, the observed rate of intussusception was not higher than the age-adjusted background rate of intussusception.
VSD Project Data May 21, 2006 through September 25, 2007
The administrative, computerized data submitted by participating MCOs to the VSD Project showed that 111,521 doses of RotaTeq were given to infants enrolled in participating MCOs. There were 3 cases of intussusception following vaccination: 1 case after dose 1 on day 20, and 2 cases after dose 2 on days 10 and 17.
The data used in this study have several limitations. First, we don't know how many cases of intussusception following RotaTeq vaccination were not reported to VAERS, and thus were not included in this study. Second, we don't know how many of the RotaTeq vaccines that were distributed were actually given. Third, the calculated background rates of intussusception based on the VSD data may not represent the general population, on which the VAERS data are based.
Available data do not indicate that RotaTeq is associated with intussusception. With more than 9 million doses of vaccine distributed during the first 19 months after licensure, data from VAERS and the VSD Project do not associate RotaTeq with intussusception. Although an intussusception risk similar in magnitude to that of the previous vaccine can be excluded, continued monitoring is necessary to assess RotaTeq's safety completely.
To read the summary please go to Postlicensure monitoring of intussusception after RotaTeq Vaccination in the United States, February 1, 2006, to September 25, 2007.
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CDC encourages health care providers and others to report cases of adverse events following vaccination to VAERS. For a copy of the vaccine reporting form, call (800) 822-7967 or visit VAERS.
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Page last modified: March 13, 2009
Content source: Immunization Safety Office