The organs and systems that work inside our body work in a very complex way, and no one can know how complicated our body parts work in order to survive, so I think we must thank God at every moment for what we are now and for the good health that we have.
It's great that you likened it to a lock and key because that is a perfect analogy to what happens in the immune systems inside our bodies.
Many viruses enter our bodies and we are always exposed to infection with any virus by picking it up from any person we meet, especially in these bad days with the presence of the Covid 19 virus, so everyone should take care of himself to protect himself, his family and those he loves from these deadly viruses.
Thank you for this valuable information you provided us in this blog.