There are back door routes to the brain. COVID vaccine developers have traversed a path through those doors. And they knew they had entered the brain by November 2020, before the vaccine rollout.
We have 86 billion neurons in the human brain, and each of those connects with 10,000 other neurons. No other structure in the known universe rivals the brain’s complexity.The brain is also the most exclusive club, so to speak, in the body. The gatekeeper is the blood-brain barrier (BBB). That barrier, shown in the second illustration below, is mostly composed of tight junctions between endothelial cells that line, in a single layer, the capillaries (our smallest blood vessels) that nourish the brain. So the BBB is in effect the capillary walls and the tight junctions between its cells.
