Vaccination does not prevent transmission, but it does reduce it.
And the only people they can transit it to that would be "at-risk" are people who've had the vaccine available to them for free, for months and chosen explicitly to not get it. That's their choice, and we should not cripple the country over it.
[1] https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/COVID-19/COV...
It's a good thing only about 2.7% of the adult population of US is immunocompromised.
We can't base policy off something that effects an extreme minority of the population, like this 2.7% statistic you cited. We'd never do anything if that were the case...
The affected people should take all necessary precautions available (get vaccinated if applicable, wear a N95 or KN95 mask, shelter isolated at home, etc). Everyone else needs to go back to work, school, stores, restaurants, etc.
If children were at serious risk here, a children vaccine would have been prioritized long ago - well before we prioritized getting vaccines to the 75 and older age group.
The entire duration of the pandemic has seen such a miniscule amount of infected children - and even fewer with serious symptoms or death - that it's absurd to base policy on this. It's statistically far more likely children will die on their way to school than become ill and experience serious complications.
We should stop basing policy off likelihoods which are prefixed by multiple zeros.