I recently read a fascinating old book called Hypothyroidism: The Unsuspected Illness by the late Dr. Broda Barnes. He thought that up to 40% of people (in the 1970s) had a thyroid condition, as indicated by frequent respiratory illnesses, menstrual problems, heart conditions, high cholesterol, etc. etc.
Interestingly nowadays it's thought that only about 4% of the population has thyroid problems (perhaps due to the popularity of the TSH test and the broad test range that's considered normal).
Dr. Barnes and his current followers believe that tracking body temperature is a good way to detect thyroid issues, especially when there's symptoms. Your waking temperature should be around 97.8 (it's lower for children). During the late afternoon it should be 98.6.
Recently there was an article in the New York Times calling for the 98.6 standard to be reduced to 98.2, because so many people now have low body temperature. This is despite the fact that a lot of body processes, for example the amylase enzyme which is crucial for carbohydrate digestion, function optimally when the body's temperature is 98.6.
So as usual we should never confuse "normal" with optimal.
Because of this I have a creeping suspicion, and I'm not alone here, that a whole line of expensive medical products from vaccines to cholesterol medications to fertility treatments are now used instead of the old style cheap thyroid medication that was used successfully for almost 100 years for a wide range of health issues. Why prescribe one medication when you can prescribe five or more?
It takes more than infectious agents to produce infection.
Infectious agents are always about us and even on and within us...we are constantly exposed to our own bacteria, viruses, and other agents capable of causing illness and we are intermittently exposed to those of other people. But as long as our resistance is high, we don't provide the conditions under which infectious agents can multiply to the point of producing illness.
Many influences can lower resistance...Low thyroid is a major function. With reduced output of thyroid hormones, every cell and every system of the body....may be affected.