The human immune system is designed to recognize foreign invaders (microbes, other substances) attack, kill, and then clear the debris away. For that reason, we must be sure that our bodies recognize our own cells as protected and the foreign ones as targets. For the first time, mRNA (Pfizer, Moderna) and adenoviral DNA (Janssen) COVID-19 vaccines install the genetic code for our bodies to make a deadly foreign protein with the aspiration that our immune system would not only respond and protect us, but also form live saving immunity from SARS-CoV-2. We have come to learn this was the drug development miscalculation of all time. Production of a foreign protein in the human body has turned out to be a disaster as illustrated by Polykretis et al in a recent paper.
Here are some of the reasons why: 1) each cell that takes up the vaccine expresses the protein in the cell surface initiating autoimmune attack, 2) the tissue distribution appears to be wide involving organs where this attack could be lethal (heart, brain, bone marrow, etc.), 3) both the genetic material and the Spike protein are long lasting (months to years) which is long enough to cause an autoimmune syndrome which may be permanent.