The skinny on flu shots


Yes, in the medical field we recommend annual flu shots for everyone. We do this for a phenomenon called herd immunity, meaning that we aim to reduce the exposure of individuals who are susceptible to severe disease by immunizing everyone. Influenza is not your typical cold virus. It has been known to cause fatal outcomes in certain populations, generally the very young, the very old, and the chronically ill — that is, people whose immune systems tend to be weaker than average. Healthy individuals with strong immune systems can contract influenza and have its manifest as nothing more than a really bad cold. However these people **are still contagious** and therefore may potentially spread the virus to others who are at risk for a worse outcome. I am typically pushier about advising someone to get the vaccine if they have regular contact with these susceptible individuals, all the more for someone who is one of them.

I have heard the argument that, “every time I get the flu shot, I get the flu.” Let’s make it clear that it is impossible for this to happen with the injected flu vaccine. In this formulation of the immunization, it is as if the virus particle has been broken in half before being introduced to the patient. A broken virus cannot replicate and therefore cannot generate infection. However the whole purpose of the vaccine is to activate your immune system to generate antibodies so that if the real flu comes along, your body will be prepared. The activation of your immune system feels a lot like how it would feel when your immune system is trying to fight off the flu in the case of an actual infection. So some people will potentially develop low-grade fevers, body aches, weakness and fatigue. This should last no more than a couple of days, and be assured that it is not an actual infection with influenza. Nasal flu vaccine (“Flumist”) does in fact contain a live virus, enough to trigger an immune response but rarely enough to cause infection.

Finally, on rare occasion a savvy patient will bring up the presence of a mercury compound in the flu vaccine. This is thiomersal, or thimerosal, which is a widely used antiseptic preservative that suppresses the growth and reproduction of common bacteria. It does metabolize the the human body to a form of mercury that can be toxic in significant amounts. However the quantity of thimerosal in a dose of flu vaccine is less than 2.5% of what is considered safe *daily* intake. Meanwhile a flu shot is needed only once a year. If you want to reduce your body’s exposure to toxic chemicals you would be better off monitoring your daily intake of sugar, salt, or artificial sweeteners. But that is a blog entry for another day. 😉

All of that said, recommendations are merely that. In medicine, we base our advice on the science of statistics. What we recommend IN GENERAL will offer protection against bad outcomes in the population. But each person needs to make a decision for his- or herself about what advice they will follow or decline. It is my goal to ensure that the decision you make rests on a foundation of solid information.

Thanks for sticking with me and reading the few entries I put out there. I have recently been taking note of the speeches I find myself giving over and over during patient visits, and I will be working on putting them into writing like this to share a bit more widely. Feel free to pass along anything you find useful! ‘Til the next time…