Get a Flu Shot, Increase Your Risk of Cancer?

The title of this post may seem alarming and dramatic, though unfortunately not exactly untrue according to a recent study* by some of the world's top virology researchers.  To preface, the authors are NOT anti-vaccine (though I hate to use that unforgiving, overused term), and in fact have spent the majority of their research careers aiming towards the formation of new and improved vaccines, quite contrarily.
The study set out with the aim of examining the immune systems of a small sample of children in order to compare the effects of vaccination (and/or lack thereof) on the immune system of healthy children and those previously diagnosed with Cystic Fibrosis (CF).   
The Scientific Findings and Rationale:
Authors found that children in both groups who were vaccinated against the flu had the same CD4 cell (see below for explanation of these terms) response as those who were unvaccinated, suggesting that this response was in fact initiated, though suggesting that a vaccine may not have been necessary to elicit this response.  However, appropriate CD8 cell (otherwise known as "killer T cells") response which was present in unvaccinated children, even as they got older, was not present in the vaccinated children.  

The Simple Explanation:

CD4 cells are "helper" cells, meaning that though they cannot kill infected cells themselves they help to mediate the immune response to such cells with various mechanisms.  CD8 cells, aka "killer T cells, are responsible for destroying cells that are infected with viruses or are malfunctioning in some similar way (such as tumor and cancer cells). 

The Bottom Line: 
This study suggests that while flu vaccines in childhood may help to prevent whatever flu strains happen to be in any particular vaccine (typically only 1-3 out of dozens of known strains) for the year they are administered, they seem to actually leave a child more vulnerable to other disease in the immediate and distant future.  Given the observed absence of the CD8 cytotoxic T cell response seen in children who were vaccinated, these children theoretically would be at higher risk for any infection or illness which thrives on malfunction within these killer T cells.  Theoretically this includes other strains of flu, Hepatitis B, and even Cancer.   

While the authors in no way seemed to set out to conclude this hypothesis, nor did they specifically mention cancer (only indirectly, via proposing the vaccine-induced malfunctions in the mechanism by which cancer manifests itself), they respectfully published their data in a seemingly honest and direct fashion, leaving room and emphasizing the need for future follow up research to further explore the surprising, albeit concerning, results.  While the study is preliminary, it may be an important factor to consider in the difficult decision of whether or not to vaccinate your child against influenza, among numerous others.