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Pediatrics. 2014 Jun;133(6):e1492-9. doi: 10.1542/peds.2013-3429.

Timely versus delayed early childhood vaccination and seizures.

Author information

1
Institute for Health Research, Kaiser Permanente Colorado, Denver, Colorado;Department of Community Health Services, Denver Health, Denver, Colorado;Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado;Department of Epidemiology, University of Colorado School of Public Health, Aurora, Colorado; simon.hambidge@dhha.org.
2
Institute for Health Research, Kaiser Permanente Colorado, Denver, Colorado;
3
Institute for Health Research, Kaiser Permanente Colorado, Denver, Colorado;Department of Epidemiology, University of Colorado School of Public Health, Aurora, Colorado;
4
Institute for Health Research, Kaiser Permanente Colorado, Denver, Colorado;Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado;
5
Department of Epidemiology, School of Public Health, University of Washington, Seattle, Washington;
6
Kaiser Permanente Vaccine Study Center, Oakland, California;
7
Department of Population Medicine, Harvard Pilgrim Health Care Institute and Harvard Medical School, Boston, Massachusetts;Division of Infectious Diseases and Department of Laboratory Medicine, Boston Children's Hospital, Boston, Massachusetts;
8
Group Health Research Institute, Seattle, Washington;
9
Department of Research and Evaluation, Southern California Kaiser Permanente, Pasadena, California;
10
Kaiser Foundation Hospital Center for Health Research, Kaiser Northwest, Portland, Oregon;
11
Health Partners Research Foundation, Minneapolis, Minnesota; and.
12
Immunization Safety Office, Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia.

Abstract

BACKGROUND:

Little is known regarding the timing of childhood vaccination and postvaccination seizures.

METHODS:

In a cohort of 323 247 US children from the Vaccine Safety Datalink born from 2004 to 2008, we analyzed the association between the timing of childhood vaccination and the first occurrence of seizure with a self-controlled case series analysis of the first doses of individual vaccines received in the first 2 years of life.

RESULTS:

In infants, there was no association between the timing of infant vaccination and postvaccination seizures. In the second year of life, the incident rate ratio (IRR) for seizures after receipt of the first measles-mumps-rubella vaccine (MMR) dose at 12 to 15 months was 2.65 (95% confidence interval [CI] 1.99-3.55); the IRR after an MMR dose at 16 to 23 months was 6.53 (95% CI 3.15-13.53). The IRR for seizures after receipt of the first measles-mumps-rubella-varicella vaccine (MMRV) dose at 12 to 15 months was 4.95 (95% CI 3.68-6.66); the IRR after an MMRV dose at 16 to 23 months was 9.80 (95% CI 4.35 -22.06).

CONCLUSIONS:

There is no increased risk of postvaccination seizure in infants regardless of timing of vaccination. In year 2, delaying MMR vaccine past 15 months of age results in a higher risk of seizures. The strength of the association is doubled with MMRV vaccine. These findings suggest that on-time vaccination is as safe with regard to seizures as delayed vaccination in the first year of life, and that delayed vaccination in the second year of life is associated with more postvaccination seizures than on-time vaccination.

KEYWORDS:

immunization; seizures; vaccine; vaccine delay; vaccine safety

PMID:
24843064
DOI:
10.1542/peds.2013-3429
[Indexed for MEDLINE]
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