Monday, August 06, 2012

Vaccines Linked To Rare Blood Disorder


Vaccines Linked To Rare Blood Disorder ITP

For a long time there has been a question regarding the safety of childhood vaccinations. Parents have been concerned over suspected links between vaccinations and multiple ailments. The U.S. Food and Drug Administration takes the position that while vaccinations may induce adverse reactions in some patients, they are safe and effective for the vast majority of children. A less widely known adverse reaction to vaccines is the development of a blood condition called ITP.
ITP (idiopathic thrombocytopenia purpura) is a bleeding disorder that results in the destruction of blood platelets. This may result in a loss of the ability for the blood to clot. This can result in hematomas, which are severe bruises that appear under the skin, as well as bruising and nosebleeds. In a very small number of cases, it may also result in bleeding in the brain. It is believed that the Measles-Mumps-Rubella-vaccine, or MMR as it is commonly referred to, can lead to ITP in a small fraction of children shortly after being given theMMR vaccine. It is not known if other vaccines can also lead to this loss of platelets.
The results of a recent study of five managed care organizations, comprising data from incidents of this platelet disorder, was analyzed. This study comprised results recorded over a nine year time period from 2000 to 2009.
Out of the close to two million children, less than two hundred developed the disorder. Children younger than seven did not show an increased risk for this disorder. Children age seven and above showed an increased risk of ITP after being administered the Hepatitis A vaccination. For children age 11-17, an increased risk was shown after receiving the chickenpox vaccine and the combination vaccine protecting against tetanus, diphtheria and whooping cough, or pertussis.
Resources:
The Risk of Immune Thrombocytopenic Purpura After Vaccination in Children and Adolescents

The Risk of Immune Thrombocytopenic Purpura After Vaccination in Children and Adolescents

  1. Robert Ball, MD, MPH, Scmd
+Author Affiliations
  1. aDepartment of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado;
  2. bChildren's Outcomes Research Program, Children's Hospital Colorado, Aurora, Colorado;
  3. cInstitute for Health Research, Kaiser Permanente Colorado, Denver, Colorado;
  4. dCenter for Biologics Evaluation and Research, Food and Drug Administration, Rockville, Maryland;
  5. eCenter for Health Research Hawaii, Kaiser Permanente Hawaii, Honolulu, Hawaii;
  6. fKaiser Permanente Vaccine Study Center, Oakland, California;
  7. gCenter for Health Research Southeast, Kaiser Permanente of Georgia, Atlanta, Georgia;
  8. hCenter for Child Health Care Studies, Department of Ambulatory Care and Prevention, Harvard Pilgrim Health Care Institute, Boston, Massachusetts; and
  9. iDivision of General Pediatrics, Children’s Hospital Boston, Massachusetts

ABSTRACT

BACKGROUND: The risk of immune thrombocytopenic purpura (ITP) after childhood vaccines other than measles-mumps-rubella vaccine (MMR) is unknown.
METHODS: Using data from 5 managed care organizations for 2000 to 2009, we identified a cohort of 1.8 million children ages 6 weeks to 17 years. Potential ITP cases were identified by using diagnostic codes and platelet counts. All cases were verified by chart review. Incidence rate ratios were calculated comparing the risk of ITP in risk (1 to 42 days after vaccination) and control periods.
RESULTS: There were 197 chart-confirmed ITP cases out of 1.8 million children in the cohort. There was no elevated risk of ITP after any vaccine in early childhood other than MMR in the 12- to 19-month age group. There was a significantly elevated risk of ITP after hepatitis A vaccine at 7 to 17 years of age, and for varicella vaccine and tetanus-diphtheria-acellular pertussis vaccine at 11 to 17 years of age. For hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines, elevated risks were based on one to two vaccine-exposed cases. Most cases were acute and mild with no long-term sequelae.
CONCLUSIONS: ITP is unlikely after early childhood vaccines other than MMR. Because of the small number of exposed cases and potential confounding, the possible association of ITP with hepatitis A, varicella, and tetanus-diphtheria-acellular pertussis vaccines in older children requires further investigation.

No comments: