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It has been speculated over the last few years whether vaccines play a part in the dramatic rise of allergies and autoimmune disease in the last four decades. The U.S. currently requires the highest number of vaccines than any developed nation and also has the highest incidence rates of autoimmune disease as well as allergies. Could there be a connection?

The National Institute of Health estimates that a shocking 23.5 million Americans suffer from an autoimmune disease. According to the American Autoimmune Diseases Related Association, however, that number should be closer to 50 million. The reason? NIH research only takes into account 24 of the 100 researched autoimmune disorders as only those 24 have good epidemiology studies to back them up.  

The CDC describes allergies as being  “among the most common medical conditions affecting children in the United States. An allergic condition is a hypersensitivity disorder in which the immune system reacts to substances in the environment that are normally considered harmless.” They also state that both food and skin allergies (some of which can be labeled autoimmune disorders) have been increasing in prevalence since 1997 in children under 18.

The theory of self/non-self recognition has dominated immunology for a very long time. This theory states that the immune system responds to pathogens (antigens) that it recognizes as foreign, or not self. Regarding vaccines, this would mean that the immune system responds to the viral matter in them and recognizes it as foreign, then forms memory to it and attacks. This is the way most people think of vaccines. However, not only is this theory overly simplistic, new research brings to light the many holes in it.

One of the biggest holes in this theory, is the lack of explanation for why our body doesn’t attack foreign protein introduced by ingestion. Much of the food we eat are proteins that are foreign and therefore not part of “self”. In addition,  we are exposed to environmental proteins on a daily basis. It doesn’t make sense that the immune system would not react to foreign proteins we eat or are exposed to, but does react when the foreign protein is injected via vaccine.

Newer immunology theories, called the danger/damage model, might help explain this disconnect and why the immune system reacts. The danger/damage model states that if there is any cellular or tissue damage occurring in the body, and that damage is associated to an unrecognized antigen (i.e. attached to a protein), the immune system will associate that protein as dangerous.

A recent article titled “Vaccine Allergies” from the National Center of Biotechnology Information (NCBI)  explores the possibility of the proteins in vaccines causing many of the hyper-sensitivies and allergies seen today. The authors state that:

“The vaccine components include active immunizing antigens, conjugating agents, preservatives, stabilizers, antimicrobial agents, adjuvants and culture media used in the preparation of the vaccine, as well as inadvertent contaminants that are introduced during vaccine handling.

Almost all the vaccine components can be considered as potential triggers of an allergic reaction.

Of particular importance are culture derived proteins from egg, gelatin and yeast. Other sources of allergic reaction are antibiotics and vaccination antigens.”

Examples of components in vaccines that may trigger allergic reactions are eggs, yeast, latex, and casein, a protein found in cow’s milk. A vaccine that uses casein, for instance, is the Tetanus-diphtheria-pertussis vaccine, commonly known as the Tdap. Several studies have found a possible link between the number of Tdap booster shots children receive and their casein allergies. Though the studies are inconclusive, the evidence is compelling.

A study published in The Journal of Allergy and Clinical Immunology notes that the children in the study “tolerated their initial vaccine but reacted to booster shots”. This suggests that the children had no milk allergies prior to receiving the first Tdap vaccination, and developed one after repeated doses. Essentially, repeated exposure to the protein via vaccine seems to result in an immune response to it.

When it comes to autoimmune diseases, studies linking them to vaccines seem to be as inconclusive as those linking allergies and vaccine proteins. However, once again, some of the findings are compelling.

The following excerpt is from a study titled DNA released from dying host cells mediates aluminum adjuvant activity. It supports beliefs regarding how all vaccine components that are protein in nature are potential candidates for the immune system to form memory to. Additionally, it entertains the notion that adjuvants in vaccines, such as aluminum, by producing cell necrosis in the host, potentially renders the host susceptible to develop an allergy to its own cells (so to speak).

“The finding that host DNA released from dying cells acts as a damage-associated molecular pattern that mediates alum adjuvant activity may increase our understanding of the mechanisms of action of current vaccines and help in the design of new adjuvants.”

In other words, there appears to be a connection between current adjuvants used in vaccines and autoimmune disorders. This study also reinforces the belief that the immune system does not just memorize foreign proteins introduced via vaccine, but rather, foreign proteins that are attached to an adjuvant that causes cell necrosis in the host. Put another way, it appears that in order to elicit an immune response from the host, a vaccine must meet the following criteria: 1. viral matter attached to a protein (to form memory), 2. Said viral matter and protein must produce cell necrosis in the host in order to appear threatening to the immune system.

Other studies have specifically focused on vaccines’ potential link to autoimmunity. A study from NCBI titled “Vaccination and autoimmunity (Vaccinosis): a dangerous liasion?” points to clear evidence of certain autoimmune disorders being caused by vaccines.

Even though the data regarding the relation between vaccination and autoimmune disease is conflicting, it seems that some autoimmune phenomena are clearly related to immunization (e.g. Guillain-Barre syndrome). The issue of the risk of vaccination remains a philosophical one, since to date the advantages of this policy have not been refuted, while the risk for autoimmune disease has not been irrevocably proved.”

What all of these studies have in common, as previously mentioned, is that they are deemed by the authors as inconclusive. While they all find good evidence to support the danger/damage model, it remains unclear whether all allergies and autoimmune disorders stem from vaccination. Likely there are many other factors contributing to the dramatic rise in prevalence of such disorders, though the fact that some of them (like Guillain-Barre Syndrome) have been definitely linked to vaccines is a step in the right direction.

Furthermore, the question of whether the growing list of vaccines in the country is linked to the growing number of allergy and autoimmune disorders remains unanswered. It is perhaps worth noting, however, that the majority of these disorders present themselves in childhood and therefore during the time when most vaccines are given. Whether or not this is relevant is still a mystery. As new research continues to emerge, hopefully the enigmas surrounding the issue of allergies and autoimmune disease will begin to be resolved. For the time being, the role vaccination plays in these disorders remains an interesting speculation.