For those that don’t want to read:
Unlike mRNA, modRNA modifies one of four compounds in RNA that make it last longer in the body, less immunogenic (reduced stimulation of the innate immune system), and more efficient at producing a protein—in this case, the spike protein, Mr. Steger stated. Since modRNA cannot target specific cells to make viral protein, it can attack perfectly healthy cells and bypass protective barriers in the body, like the blood-brain barrier.
Injecting modRNA into the body may lead to adverse events like strokes, cardiovascular complications, pulmonary embolism, and the formation of blood clots—many of which were disclosed in Pfizer’s documents (pdf) but were not attributed to its product.