There's something that's been repeated by a few guests on the show as well as in that video above -- "Dr. Thomas Cowan Covid19 fails Koch's postulates" -- that really bothers me.
So, Koch's postulates were developed in the early days of germ theory as a way to try to investigate if something was or was not due to an infectious cause. Imagine in those days seeing patients with a lot of respiratory illnesses or skin conditions and trying to figure out what's causing it, when you only have a vague idea of the relationship between the bacteria you can see under a microscope and the patient's condition. So Robert Koch came up with a basic concept for determining whether something is or is not caused by microorganisms.
Here are Koch's postulates:
1) The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
2) The microorganism must be isolated from a diseased organism and grown in pure culture
3) The cultured microorganism should cause disease when introduced into a healthy organism.
4) The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
The problem is, these are horribly out of date and do not reflect our modern understanding of microorganisms and the way they cause disease. Even Koch had moved away from them after he continued to learn more throughout his career.
Some basic issues with those postulates:
1) "microorganism...should not be found in healthy organisms."
- we know that tons of people have potentially-disease-causing bacteria living all over their bodies, yet those bacteria do not cause disease. Staph skin infections, urinary tract infections, many kinds of pneumonia -- those are just a tiny example of the very common infections caused by bacteria already living in/on our bodies in our normal, completely healthy state.
2) "and grown in pure culture"
- there are lots of bacteria that are very difficult to grow, and even though they were present, would not have been able to grow on any culture media that Koch and his peers would have known to create. So "I can't grow it" is not proof of anything in Koch's day.
3) "microorganism should cause disease when introduced into a healthy organism"
- again, we know this to be clearly false. Even non-medical people can understand through common sense that if you come into contact with someone who is sick, get some pus from their infected wound on your skin, etc., that you only have a chance of getting sick yourself. It's not a sure thing.
So, when I hear someone say "COVID fails Koch's postulates", I'm like DUH. Because we know that you can have a virus in your body without having symptoms, and we know that not everyone who gets exposed to a virus is going to get the illness.
It's hard to hear someone make that claim from the standpoint of "Hey listen to me, I know things about infectious disease", and not immediately disregard everything else they say. It's such a basic thing to get wrong and such a weak point to make.
