[DugwayDuke]

mom.mom wrote: “It’s a 2017 article. The point is that the mRNA technology had problems with safety in the past. How have they solved that?”

The article doesn’t attribute the safety issues with that particular treatment with the mRNA technology. Do any of the other articles you reference do so?

[RC one]

The problem was that the mouse's immune system attacked the mRNA before it could get into the mouse's muscle cells where it could produce the desired protein e.g the spike protein in this case. The problem was solved back around 2017 with the discovery of modified nucleosides.