Adverse reactions to vaccines tend to occur in the first 2 months. Use of mRNA in vaccines has been studied for 2 decades. The first mRNA vaccine trial (human) was in 2009. Its not hard to research this, here's a useful article from the Children's Hospital of Philadelphia.
Feature Article: Long-term Side Effects of COVID-19 Vaccine? What We Know. | Children's Hospital of Philadelphia (chop.edu)
I attended a webinar hosted by a local HS a few weeks ago, where 3 Doctors reiterated the same thing (LT effects), and refuted a wealth of nonsense parents had complained about due to the COVID protocols the HS had put in place, using empirical evidence from reputable sources versus, you know, anonymous statements/positions/opinions from the internet.
BTW, when asked to comment on the low death rate for HS age, they were adamant that HS students should vaccinate. Basically, its about biology & science and preventing community spread. WRT risk of death, the pediatrician from Phoenix Childrens hospital put it this way (not a direct quote, but close enough), "After being on the front lines of this for the past 18 months, healthy kids get sick from COVID, healthy kids end up in hospital from COVID, healthy kids end up in ICU from COVID and healthy kids end up permanently disabled from COVID."
A friend of mine who is also a Doctor at Phoenix Childrens Hospital said they entered "code red" in late August (not sure if they still are). This was caused by the surge in COVID cases (back to school). It means that they were at capacity, i.e. they could admit no more patients. Her kids are vaccinated, she had zero hesitation.
As for the whole conspiracy theory piece, here's another interesting read for you, from a virologist in the UK whose work was hijacked and (selectively) used by anti-vaxers. He put his name to it, so, you know, not anonymous
As a virologist I’m shocked my work has been hijacked by anti-vaxxers | David LV Bauer | The Guardian