With all due respect, Harry, you need to turn off the news, CNN, or wherever you're getting this fear-mongering disguised as information.
1. Between the existing science/understanding of similar viruses, and nearly 1.5 years worth of data on this one, yes, we do have a pretty good idea of the minimal to non-existent long-term effects of Covid. These new types of vaccines? While yes we probably have enough scientific understanding to say they are *most likely safe* in the long term, with literally no data on that, there has to be more confidence in our knowledge of the long term effects of Covid vs these new vaccines.
2. Asymptomatic spread, wut? Are you actually unaware that the hypothesis of asymptomatic spread never actually turned out to be a thing? I thought everyone knew that by now, but in case you don't know, you can relax on that. It never turned out to be real (just like as is the case with all other respiratory viruses). Asymptomatic spread is not a thing. That's well known at this point.
3. Variants... {sigh} Yes, it's technically possible that a more deadly/virulent variant could get a foothold, but generally speaking, variants are how viruses like this evolve to be LESS virulent. Natural selection applies to viruses as well, and success for a virus is most tied to transmission and not being harmful to its hosts. This is how the spanish flu that killed millions of people at one point evolved to be just another seasonal flu virus.
So, yes, on a micro level, we want to keep an eye on known variants for a few different reasons. But on a macro level -- in general -- not only shouldn't we fear variants, we should welcome them. They are the path to this virus becoming something we never think about again.