What have we learned about mRNA vaccination in the last two years?

Derek Lowe had a review about testing of mRNA flu vaccines and they were not better than current ones. In a way they could be even worse because they had more side effects.

I heard about mRNA vaccine trials for cancer. I don't know the results.

Overall, the main strength of mRNA vaccines could be easier manufacturing. Will they prove to be more effective? I don't know but probably not.

I would guess we're too early to see much if the truly long term affects, if there are any. The data quality of VAERS is a joke, so anything sufficiently rare that has other normal causes will likely be hard to find.

As an anecdote, I had months of intermittent inflammation in the armpit and chest on the side I recieved the vaccines in. This had never happened with any other vaccines. The doctors had no explaination and ran multiple tests. It wasn't until the ultrasound tech mentioned the shots that it crossed my mind it could be them. No idea if I will have further issues, or if months of inflammation could lead to longer term issues.

While not exactly mRNA vaccines, I think we will ultimately see the use of RNAi as a way to modulate gene expression in humans. It's already being done in many organisms. Imagine a technology that can perform RNAseq via some wearable instrument like an apple watch or an implant. We'll collect temporal gene expression data on important physiological functions, and address the results with a pill containing some stable RNAi molecule which will downregulate that function.