Nanoparticles are what the mRNA SARS-CoV-2 vaccine are packaged in. They're lipid particles that are chemically very similar to your cell walls so they just fu

Nanoparticles are what the mRNA SARS-CoV-2 vaccine are packaged in. They're lipid particles that are chemically very similar to your cell walls so they just fuse with the wall and then release their payload inside the cell. That doesn't have anything to do with the target though. The stalk of the virus is difficult to target and not really possible with the existing way that influenza vaccines are manufactured with an inactivated virus process. So you wind up with the whole proteins and no good way to target segments. By using mRNA technology you can specify which protein you want to target or which segment of protein you want to target. It can also be useful to make edits to the protein sequence like the prefusion stabilization in the mRNA vaccines. When you get the inactivated influenza vaccine you're still getting HA stalks attached to the HA protein and for whatever reason the immune system doesn't target the stalk sections well. So the idea is that you hit the immune system with a payload of only HA stalks and then hopefully the immune system pumps out antibodies specific for that which will then be resistant to genetic drift.