Germ Theory & Terrain Theory

When it comes to how we get sick, there are two theories: germ theory and terrain theory. (And when I say theory, I mean like how gravity is a theory; not how your aunt twice-removed has a “theory” about microchips in vaccines.)

Germ Theory

Germ theory is what most of us are already acquainted with: you get exposed to germs and then you have a chance of getting sick. The number of germs and the length of your exposure are what determine how likely you are to get sick and how sick you will get.

For example, if you are exposed to a small number of germs for a few minutes, the chances of you getting sick at all are small, and your case would likely be mild. This principle is the driving force behind vaccines – your body is exposed to a very small dose of a pathogen so that your body can easily fight it, but now recognizes it for the invader it is so you are more prepared for a larger invading force in the future.

But say that you have a sick child cough right in your face (that never happens ?), you were just exposed to a BIG viral load all at once. Your chances of getting sick are much higher, and because you were exposed to more germs, you are more likely to get a more moderate to severe case. This principle is the reason behind masks and social distancing – the masks hopefully reduce the number of viruses coming in/going out and the 6-foot distance is hard for many of them to travel and survive.

(Without getting into a longer discussion, in my opinion, the best solution when you are sick is to STAY HOME. Because masks and social distance do not prevent 100%, not to mention viral shedding, so the only way to guarantee you do not infect others is to not be around others.)

Terrain Theory

Terrain theory is the theory behind how healthy your immune system is and thus how well it works.

Imagine your immune system is like a garden: the more well-kept it is, the easier it is to spot the weeds and remove them before they get out of control. The messier your garden, the more likely you are to overlook the weeds and then one day, BAM! Now you have to do a lot more work to clean up than if you just did a little bit every day. (“An ounce of prevention is worth a pound of cure.”)

This terrain theory is why two people can both be exposed to a sick person but then one person catches it while the other doesn’t. (Or one gets a very mild case, while the other ends up in the ER. You hear about this happening with Covid-19 all of the time.)


The strict definition of a comorbidity is having more than one illness/disease at the same time (multimorbidity is having two or more).

The most common comorbidities the increase your chances of getting severely ill from Covid-19 are cancer, chronic kidney disease, chronic liver disease (such as fatty liver), chronic lung issues (like asthma, COPD, cystic fibrosis, etc.), dementia and Alzheimer’s, Type I or II Diabetes, Down Syndrome, heart disease, strokes, any immunocompromising condition, overweight and obesity, smoking, organ transplant, Sickle Cell anemia, and more.

Historically, terrain theory has been largely ignored when discussing how we get sick, but Covid-19 has especially made it clear that it is a critical part of the immune puzzle. Those who have underlying health issues are the ones being most negatively impacted by Covid-19.

What Can I Do?

If possible, it is important to address your underlying health challenges. You cannot control the people around you, but you can control yourself. (And honestly, worrying about or being angry at everyone around you constantly is not good for your own health!)

  • Get enough sleep (a regular bedtime and wake up time help enormously)
  • Drink plenty of water
  • Exercise regularly (even if it is just a walk!)
  • Meditate or practice gratitude – positive thinking helps both mentally and physically
  • Engage with alternative practices that help your body work better, such as chiropractic, acupuncture, and massage
  • Eat cleaner (sugar is the root cause of many chronic diseases and it impairs your immune system’s function significantly)
  • Take your immune boosting supplements

Let’s be real: every single person on the planet has been or will be exposed to Covid. It is simply too infectious to be stopped. (They even had an outbreak in ANTARTICA where everyone is vaccinated and obviously there is minimal exposure.) But by taking control of your health as best you can, you minimize the chances of you becoming seriously ill (or getting sick in the first place).

Need chiropractic or acupuncture? Want to clean up your diet? Interested in supplements that can help your immune system work better? Call 978-237-5106 to schedule an appointment with Dr. Pulley!