At least in the article about reverse engineering the vaccine, they state that that "The mRNA vaccines quickly degrade in the human body" https://berthub.eu/articles/posts/reverse-engineering-source...
I think also the instability is a large component of why the vaccines must be stored at such low temperatures.
Edit: As noted in a comment, the half-life for the vaccine-related mRNA strands are longer, by design, so they produce more spike protein, but they remain fairly transient.
Look at the section 4.1. Molecular Stabilization. Yes, it is a challenge, but a challenge that has been overcome.
Your body knows how to handle all of those perfectly well, and yes, most of them will be excreted.
First I think it is quite incredible to have such a vaccination out so quickly. As the pandemic eases are we in a situation needing to continue booster shots say on some reoccurring basis as a preventative measure? I am not very clear on the virus itself whether it eventually gets eradicated over time. Or something a bit more reactive where it is possible to get a shot after infected or having symptoms and whether mRNA works in this way as well on a reactive basis.
Most likely. SARS-CoV-2 is now endemic in the human population & unlikely to die out. The general impression in the scientific community is that the current set of vaccines should be protective for at least a year or two, at which point variants will have emerged that evade the vaccines developed on the Wuhan strain. Booster shots developed on these new variants would be required for the foreseeable future.
> Or something a bit more reactive where it is possible to get a shot after infected or having symptoms and whether mRNA works in this way as well on a reactive basis.
In principle this is possible - some vaccines are capable of arresting an active infection, though that is highly specific to certain pathogens. This is not something current COVID vaccines can do.
This was the first large-scale use of this kind of vaccine so it is an amazing field test of the process. Normally that would be a slower, incremental process but the risk from Covid forced them to simplify and speed up the process.
https://www.mskcc.org/coronavirus/what-s-different-about-mes...
Immunity as a service, with subscription model.
Do these injected mRNA eventually phase out and die out from the body? Typically what is the lifetime? Is there also some 'off' mode, or complementary vaccine to undo an injection say after learning of some serious affect?