Immune Education Series: Exposure Does NOT Equal Disease

illustration by Aaron McMichael, DC

The covid-19 / coronavirus pandemic has shown that everyone exposed to a virus or infectious microbe does not experience disease. Few experience severe illness and many don’t even experience mild symptoms. If disease is as simple as being exposed to a germ, why do some people avoid becoming sick?
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What Happens With Exposure to Coronavirus?
Exposure does not equal infection and infection does not equal illness. The graphic below illustrates possible outcomes of exposure to coronavirus. Data indicates that 80% or more of confirmed cases of infection do not experience significant symptoms of illness. So, the large majority of those exposed and infected do not even know it because they do not become ill. This does not account for the even greater number of those exposed to coronavirus but have not been confirmed due to a lack of symptoms and limited testing. As testing increases, we may find that more than 90% of those exposed do not become sick. Some exposed cases may not test positive due to strong resistance or low exposure.

Of the less than 20% of confirmed cases that experience symptoms of illness with coronavirus, most are mild and fewer are severe. An even smaller fraction (those with pre-existing health problems) experience such severe illness it leads to death (see our article about pre-existing conditions).

As you can see in the picture, confirmed cases can be illustrated as a triangle, with a large majority experiencing no illness, and ever smaller portions experiencing greater degrees of illness or death. Surrounding that is the unknown (likely large) number of those exposed but not confirmed cases. Though infectious diseases can vary in transmission and virulence, this is similar to the presentation of many illnesses.

Reducing Risks
We are exposed to good and bad microbes every minute of the day and most of the time we experience little effect on our health as our immune system does its job. Many microbes are essential to our health, serving as a layer of protection or aiding our digestion among other benefits.
For those viruses or microbes that may be harmful, we have three ways to assist the body’s natural fighting ability:

1. Reduce exposure – there has been significant debate over the effectiveness of various methods (cleaning, gloves, masks, etc.), but these methods are all potential ways to reduce exposure and therefor risk of illness
2. Improve health to minimize risk of illness – less information has been shared on how to support our immune system to prevent or minimize illness. These methods include healthy lifestyle habits like regular exercise, nutritious eating, adequate sleep, and stress-reducing activities to increase resistance to infection.
3. Health care once illness has occurred – for the minority of those infected that experience more significant illness, health care is of course provided to counteract the infection.

The best strategy is to take reasonable steps to not only reduce exposure, but especially work to improve your health and reduce your risk of a severe infection.

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