No significant relationship was found between routine childhood vaccines and hospitalizations for nontargeted infections in a population-based study of 805,206 children under 5 years old, said Anders Hviid, M.Sc., and colleagues at the Statens Serum Institut in Copenhagen.
The complex nature of current routine vaccinations has prompted concern that children might suffer immune dysfunction and become vulnerable to diseases not targeted by the vaccines (JAMA 2005; 294:699–705).
The population-based study examined six vaccines and seven infectious disease categories for a total of 42 possible associations. There was one adverse association during 2,900,463 person-years of follow-up that occurred between the Haemophilus influenzae type b vaccine and acute upper respiratory tract infections, with an incident rate ratio of 1.05.
There was one adverse association of the incident rate ratios for vaccinated children within the 14-day lag period relative to unvaccinated children that occurred between the MMR vaccine and acute upper respiratory tract infections, with a nonsignificant incident rate ratio of 1.10. None of the incident rate ratios increased by more than 10% between vaccinated and unvaccinated children. The increase in the incident rate of hospitalizations per dose of vaccine was calculated, and yielded an incident rate ratio of 0.94 for viral pneumonia, 0.96 for bacterial pneumonia, 0.98 for septicemia, 0.99 for viral CNS infections, 0.99 for diarrhea, 0.99 for acute upper respiratory tract infections, and 1.00 for bacterial meningitis.
Other vaccines studied were diphtheria-tetanus-inactivated poliovirus, diphtheria-tetanus-acellular pertussis-inactivated poliovirus, whole-cell pertussis, and oral poliovirus.