Researchers had shown that the pre-existent belief, of children who had received multiple vaccinations may have to be hospitalized more often for other diseases, is a myth and nothing else. The research report was published in the latest issue of JAMA.
During the last 2 decades, more vaccinations have become available and routine vaccination schedules have become increasingly complex, according to background information in the article. This has led to concern among some that multiple antigen vaccines, such as the measles-mumps-rubella vaccine, or aggregated vaccine exposure could lead to immune dysfunction, resulting in infectious diseases not targeted by vaccination, occurring as a result of an "overload" mechanism.
However, epidemiological and clinical support for the effect has been lacking, and some studies have even favored a beneficial effect on non-targeted infectious diseases.
Researchers of the Statens Serum Institut, Copenhagen, Denmark, had evaluated the relationship between routinely administered childhood vaccines (Haemophilus influenzae type b; diphtheria-tetanus-inactivated poliovirus; diphtheria-tetanus-acellular pertussis-inactivated poliovirus; whole-cell pertussis; measles-mumps-rubella; oral poliovirus) and hospitalization for non-targeted infectious diseases.
The population-based study included all children born in Denmark from 1990 through 2001 (n = 805,206). Information was collected on type and number of vaccine doses received and hospitalization with infectious diseases, specifically acute upper respiratory tract infection, viral and bacterial pneumonia, septicemia (an infection of the blood stream), viral central nervous system infection, bacterial meningitis, and diarrhea.
The researchers found that of 42 possible associations (6 vaccines and 7 infectious disease categories), the only adverse association was for Haemophilus influenzae type b vaccine and acute upper respiratory tract infection. This one adverse association was within the limits of what would be expected by chance alone and the effect was not temporal or dose-response.
Conversely, the 15 observed protective associations suggest that vaccination may have non-targeted protective effects. When considering aggregated vaccine exposure, the researchers found no adverse associations between an increasing number of vaccinations and non-targeted infectious disease hospitalizations.
The researchers feel that their results do not support the hypothesis of increased risk of non-targeted infectious disease hospitalization after childhood vaccination.