I’ll take my skewering - I did mean to check whether the adenoviruses inserted mRNA or some other form of nucleic acid coding the protein, but didn’t.
I wasn’t trying to be mean-spirited, and I apologise to all if it came over that way.
There is a perception among those opposed to the vaccines that mRNA vaccines do something new in cells, and that the cells change in some way (i.e. “learn” ) how to produce the spike protein. Neither of these things are strictly true - cells gain a temporary instruction to do something, and they just follow those instructions as they would with any other mRNA, and once the instructions are gone, they stop. Other cells responsible for antibody production do learn, which is how we get long term immunity. I dislike any terminology that feeds into unscientific and inaccurate depictions of how the vaccines actually operate.
And I do agree, the mRNA delivery mechanism is new, and gamechanging - it allows rapid production of new vaccines and new approaches to diseases that have so far proved intractable to vaccinate against. I didn’t mean to detract from that achievement.
This is certainly a valid point, and a drawback to the use of the informal word “learn”, at least when your audience is determined to assume the worst.
You could go further, and say that a priori we should expect mRNA vaccines to be safer than DNA (adenovirus) vaccines in terms of unforeseen lasting effect on the genome. When DNA is present it a cell, it is in principle possible in rare events for it to end up incorporated permanently in the genome. Over half the human genome is made up of transposable elements that (when active in our evolutionary history) moved around through cut-and-paste or copy-and-paste machinery. But this happened in the germline over evolutionary time. Such changes to the genome over “lifetime” timescales are extremely rare. It is also possible for RNA to end up permanently incorporated in the genome, but the possibility is an order of magnitude more remote, because it requires a reverse transcriptase enzyme to first convert the RNA back to DNA. Reverse transcription does not normally take place in cellular metabolism, so it would require the presence of a reverse transcriptase from a different viral infection in the same cell, or from one of the very few active transposable elements in the genome.
There was a paper describing the possibility of integration of the SARS-Cov-2 virus itself (which is RNA) into the genome, perhaps explaining some prolonged false positives. I’m not sure if much has come of this since.
This thread is making me want to rewatch Cells at Work!, an anime in which the characters are all cells. The two main characters are a red blood cell and a white blood cell (neutrophil). There are quite a few immune-related cells highlighted in different episodes.