OK, so you brought in some unquantified covid effects that you then said are irrelevant. I agree, they are irrelevant because they are too rare.
Can you please quote a single VE longitudinal study with at least 6 months duration that shows stable VE? Even VE against severe infection is declining by about 10% around from 92% to 82%. UK PHE VE reports, which is as close to a real-time VE indicator as we'll ever have (short of FDA/CDC actually doing their jobs) show a steady decline week after week. The trouble is that VE against symptomatic infection drops off a cliff around the 6 months point, so it's entirely rational to wonder if VE against severe infection doesn't also fall off a cliff, only a few months delayed. We don't have data at 9/12/etc months, so we have to wait. Looks like you are indeed concerned about this very problem and decided to boost. Good for you. Myself, I really wish the vaccines perform well over time. But can't help notice that the (meager) data we have so far doesn't support the wish, and being faced with medicine that lost its effectiveness over a long period of time earlier in life to the point of being a wash, I'm less enthused about boosting on a regular basis.
In the context of kid vaccinations though, the whole situation is ridiculous. Covid health risks for kids are minimal. Pfizer own admitted unscientific application (aka we can p-hack whatever metrics we want to prop our side of the argument) estimates they might save only one life in a million, and hospitalization in low hundreds in a million, same order of magnitude as myocarditis adverse effects. That means one million kids need to be jabbed to see any positive effect. Given that there are longterm risks with any novel intervention that we don't know about yet, this is an entirely unnecessary medical intervention that borders on criminal negligence.
As a philosophic note, life has risks, even for kids: https://www.vox.com/22699019/covid-19-children-kids-risk-hos... We fundamentally can't eliminate all risk, we have to learn to live with risk. What other risks than myocarditis, you may ask. An excerpt from a 2011 paper summarizing why dengue vaccines failed:
"Original antigenic sin has the advantage that a response can be rapidly mobilized from memory. However, the downside is that in some cases, such as dengue, the response is dominated by inferior-quality antibody. In influenza, original antigenic sin has been shown to reduce the effectiveness of vaccination (13, 34, 51). In dengue, the effect of original antigenic sin has considerable bearing on vaccine strategies. Once a response has been established, it is unlikely that repeat boosting will be able to change its scope, meaning that balanced responses against the four virus serotypes will need to be established with the first vaccine dose."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014204
PS. Whomever feels the urge to retort that kids taking the vaccines somehow saves grandma, please stop. Besides being creepy (we don't put kids at risk to save elders, ever) and nasty (quite the guilt load on young shoulders being thrown around), it doesn't. By now there is multiple evidence showing that VE against infection fading to irrelevancy after 6-9 months. Unless there is a credible longitudinal study showing the contrary, this particular matter is closed.