~ A thing can be effective without being 100% effective. No-one ever said that vaccines were 100% protective against infection. But they are, as the data indicate perfectly clearly, extremely protective against infection, particularly symptomatic infection. If you have been vaccinated, you are less likely to catch Covid. If you have been vaccinated and do catch Covid, then you are less likely to cough it out over someone else. Vaccination reduces the spread. This is not complicated.
Global herd immunity is unlikely. Effective herd immunity within a population may be achievable, if everyone is vaccinated (or has caught the virus). People who have not had the virus, who refuse the vaccine when offered, are actively working against achieving herd immunity.
Very nicely put. On the one hand there's no unnecessary info, and there's everything you need to know, on the other.
I just want to emphasize that although it's less common, some children do have severe complications after catching COVID-19, and unvaccinated adults pose a threat to them. It's no longer a private matter, I'm afraid.