Evelyn Coggins wrote about the upside of the flu shot, and how the vaccination works, last month on the Wellness Almanac. Check out that post, here.

I opened the door and in-flew-Enza.

The resident biology teacher at my junior high school wrote that joke on the board on the first day of every unsuspecting grade 8 biology class he ever taught. He was a legend in his own mind.

He didn’t seem to realize that flu isn’t funny.  I routinely listen to people who are stunned by the awfulness of flu symptoms and the speed with which it strikes. It’s not an experience that sufferers are eager to revisit.

In my last entry, I spoke about the mechanism by which the flu shot can help prevent infection and some really good reasons why people may want to consider getting one. Today I promised to discuss some of the associated risks.

An important downside of the flu shot is that things can go horribly, unpredictably wrong for some people. Dr. Nick Kelley, PhD co-authored a comprehensive  analysis of flu vaccines for CIDRAP and observed, “There is a lot we don’t understand about influenza, influenza vaccines ….and influenza immunology.”

On a good day, the immune system contentedly sifts through the vast number of cells gettin’ down in our bodies. In essence, it performs ongoing, routine security checks and categorizes the cells as friends or foes… Red blood cell? – one of us. Armpit hair? – unloved, unwanted, ripped out with hot wax but family. Heart muscle? – stand down soldiers.

Discovery of an invader triggers alarms and initiates search and destroy missions. Unfortunately, the need for speed in this situation can lead to identification errors not unlike George Bush’s infamous ‘weapons of mass destruction’. When the immune system makes identification errors, contact with innocuous molecules such as dust, dander, bubblegum-flavored lipstick can result in an allergic response. The implications of an allergic response can range from transient misery to life-threatening catastrophe for the individual affected.

Sometimes, God forbid, our bodies become casualties of friendly fire as the immune system targets our own healthy tissues for destruction. This type of error results in the onset and progression of autoimmune disorders such as Lupus, rheumatoid arthritis, multiple sclerosis and juvenile diabetes. This process seems to be triggered by foreign molecules resembling our own cells such that the immune system mistakenly continues to target our look-alike cells long after the infection has been stamped out.

These inappropriate responses can be triggered by certain antibiotics and other drugs.

Sometimes errors occur than nobody expects or understands. During the 2009 H1N1 (swine flu) pandemic, Canadian researchers reported a greater incidence of infection in people who had been vaccinated against the seasonal flu. These people were much more sick than usual and more likely (2.4%)  to need medical intervention and hospitalization compared to those who did not get the vaccine.

This phenomenon is known to experts. It has a name – ‘vaccine-associated enhanced respiratory disease (VAERD’) – and has been observed in the past with another type of viral vaccine. Based on experiments with piglets, experts believe some vaccines may be capable of enhancing the diseases they are designed to prevent depending on where the antibody (arrest warrant) is attached to the virus – but nobody knows for sure.

At any rate, something similar seems to be afoot this year. Experts are surprised by the sheer number of people getting really sick with H1N1 when they expected the majority of us to have built immunity to it either via vaccination or previous exposure.

The take home message regarding flu vaccines and medications is that there are no guarantees of immunity or completely safe therapies. If we understand this, we are in a better position to weigh the risks and benefits of the health decisions we are called upon to make.

Tune in again for a discussion of  the dangers of over-the-counter flu medications as well as suggestions for herbal-based therapeutic strategies that are effective for cold and flu symptoms.

FYI, none of them will result in you going back to work within 24 hours. Just putting it out there…