Do childhood vaccines cause ashtma?

Admittedly, this study (pdf) does show a positive association between aluminum in vaccines given before the age of two was found and developing childhood asthma between the ages of 2 of 5. However, it is a retrospective study (pdf) that generally cannot establish a causal relationship between a risk factor (aluminum in vaccines) and an observed outcome (asthma). You can’t assume, based on this study, that vaccines caused the observed asthma.

Retrospective studies look back on data collected before the study was designed. Data that would have the potential to impact the observed outcome may not have been collected as it would have in a prospective study.

Let’s consider a few items concerning the results of this study. Young children have many opportunities for aluminum exposure. Aluminum is the third most abundant element on earth and is present in many of the foods we eat, in much higher quantities than found in vaccines. Any aluminum injected from vaccines is metabolized in the body, and the vast majority of it is excreted within weeks.

Retrospective studies are very good at finding associations that need further exploration and testing. Now that a positive correlation has aluminum and asthma has been identified, further studies with different study designs need to be conducted to determine what may actually be causing the increase in asthma. No study at this point, including this one, has suggested that vaccines are the cause of increases in childhood asthma rates.

This study does show that the CDC takes vaccine safety very seriously and that our monitoring systems work.