Hygiene Hypothesis vs. Influenza Vaccine


It’s that season again! Pharmacies are stocked up and ready to roll out the new flu vaccines. While pharmacists are known to be strong advocates of the flu shot, it’s important to take a look at the actual vaccination rates and analyze some of the reasons behind the trends. According to Statistics Canada and the 2014 Canadian Community Health Survey, only 32% of Canadians receive vaccinations against the Flu.

The reluctance to get vaccinated could be related to the weariness surrounding new vaccines, but also because of the outdated sentiment that getting the flu is a natural part of life and may be even be vital to strengthening the immune system.

The idea behind this rationale is that it’s better to get the actual disease than to have an artificial vaccination against it.

This idea that illness is good for children, or anyone for that matter, is unequivocally wrong. In 1989, David Stratchan, an epidemiologist in Britain, came up with the “Hygiene Hypothesis” in which he observed that babies born into households with many children or who attended daycare, were less likely to develop asthma and allergies when compared to the general population.

He hypothesized that the innate protection against asthma and allergies came from the exposure to these illnesses amongst other children. In essence, the theory claims that children who are brought up “dirty” and exposed to viruses and bacteria are less likely to get sick as an adult.

Follow-up studies that spanned decades disproved this linkage between illness and protection against these inflammatory disorders, and actually found that early exposure to these illnesses could make the prognosis worse.

Some studies actually showed that individuals who endured more infections during childhood had a greater propensity to die of premature death.

The linkage that was observed in Stratchan’s hygiene hypothesis can be attributed to the ample exposure to harmless natural bacteria, such as those found on dirt, animals and on other children, as opposed to disease-causing bacteria like the influenza virus.

There is nothing “natural” about the influenza virus which is mutating strain that is becoming difficult to eradicate. One of the most compelling reasons to get a fu shot is that MRSA is widespread and causing pneumonia outbreaks as a result of flu complications among healthy individuals

Sure, getting the flu shot does not grant you full immunity from getting MRSA pneumonia, but getting vaccinated will reduce the risk.

High-risk populations such as children, geriatrics, pregnant women and those with comorbid conditions would benefit from immunization as they have the highest risk of serious flu complications, which can cause extended hospitalizations and even death.

There are many reasons why the hygiene hypothesis should have absolutely nothing to do with vaccinations. The diseases that vaccines prevent occur independent of the level of hygiene in the sanitation.

If we look historically, Varicella (chickenpox) occurred in everybody independent of what country they lived in. The same proved true of Measles, Mumps and Rubella.

As pharmacists, we are in a good position to dispel myths and give our patients sound, evidence-based advice. We should help them make informed decisions, while at the same time respecting their autonomy.

We want to hear your thoughts on this. What are some of the explanations you hear from patients about why they avoid the flu vaccine?