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Childhood vaccinations and risk of asthma
Frank DeStefano1, David Gu, Piotr Kramarz
1Centers for Disease Control and Prevention, Atlanta, GA, USA.
Insights
Childhood vaccinations, including diphtheria, tetanus, whole cell pertussis, oral polio, and MMR vaccines, do not increase asthma risk. Weak associations for Hib and hepatitis B vaccines may be due to healthcare use or information bias.
Area of Science:
- Pediatric Health
- Immunology
- Epidemiology
Background:
- Previous studies suggested a link between childhood vaccines and increased asthma risk.
- This study investigated the association between various childhood vaccinations and the risk of developing asthma.
Purpose of the Study:
- To evaluate the association between childhood vaccinations and the subsequent risk of asthma.
- To determine if specific vaccines, such as whole cell pertussis, are linked to asthma development.
Main Methods:
- A cohort study of 167,240 children was conducted from 1991-1997.
- Vaccination status was tracked via computerized systems, and asthma onset was identified through medical records and pharmacy data.
- Follow-up ranged from 18 months to 6 years of age.
Main Results:
- 11.0% of children developed asthma by a median age of 11 months.
- No significant association was found for diphtheria, tetanus, whole cell pertussis, oral polio, or MMR vaccines.
- Relative risks for Haemophilus influenzae type b (Hib) and hepatitis B vaccines were slightly elevated (1.18 and 1.20, respectively).
Conclusions:
- Diphtheria, tetanus, whole cell pertussis, oral polio, and MMR vaccines are not associated with an increased risk of asthma.
- The observed weak associations for Hib and hepatitis B vaccines are likely explained by confounding factors like healthcare utilization or information bias.
Background:
A few previous studies have suggested that childhood vaccines, particularly whole cell pertussis vaccine, may increase the risk of asthma. We evaluated the suggested association between childhood vaccinations and risk of asthma.
Methods:
Cohort study involving 167,240 children who were enrolled in 4 large health maintenance organizations during 1991 to 1997, with follow-up from birth until at least 18 months to a maximum of 6 years of age. Vaccinations were ascertained through computerized immunization tracking systems, and onset of asthma was identified through computerized data on medical care encounters and medication dispensings.
Results:
In the study 18,407 children (11.0%) developed asthma, with a median age at onset of 11 months. The relative risks (95% confidence intervals) of asthma were: 0.92 (0.83 to 1.02) for diphtheria, tetanus and whole cell pertussis vaccine; 1.09 (0.9 to 1.23) for oral polio vaccine; 0.97 (0.91 to 1.04) for measles, mumps and rubella (MMR) vaccine; 1.18 (1.02 to 1.36) for Haemophilus influenzae type b (Hib); and 1.20 (1.13 to 1.27) for hepatitis B vaccine. The Hib result was not consistent across health maintenance organizations. In a subanalysis restricted to children who had at least 2 medical care encounters during their first year, the relative risks decreased to 1.07 (0.71 to 1.60) for Hib and 1.09 (0.88 to 1.34) for hepatitis B vaccine.
Conclusion:
There is no association between diphtheria, tetanus and whole cell pertussis vaccine, oral polio vaccine or measles, mumps and rubella vaccine and the risk of asthma. The weak associations for Hib and hepatitis B vaccines seem to be at least partially accounted for by health care utilization or information bias.