mRNA COVID vaccines use the organelles in your cells to make partial copies of the novel coronavirus, which is exactly how the live novel coronavirus grows in your body.
The big difference is that the copies cannot make copies of themselves (they are only partial copies) so the viral load does not grow geometrically within your body.
Again: if the small viral load of a vaccine makes a person sick for a week, that person likely has a higher risk for severe illness from the (much larger) live viral load from a full infection.
Science does not yet understand why some people have more severe COVID illness than others, but it is an observed fact that some do. In some cases, even if they are otherwise fit and healthy.
The big difference is that the copies cannot make copies of themselves (they are only partial copies) so the viral load does not grow geometrically within your body.
Again: if the small viral load of a vaccine makes a person sick for a week, that person likely has a higher risk for severe illness from the (much larger) live viral load from a full infection.
Science does not yet understand why some people have more severe COVID illness than others, but it is an observed fact that some do. In some cases, even if they are otherwise fit and healthy.