Immunity against one variant isn't the same as against others, depending on how much the virus mutates. The decreased efficacy of vaccines is in part due to this. Example- Why flu shots are revised every year is based on S. Hemisphere or other predominant circulating viruses that summer. And, remember, herd immunity is the least desirable way to become immune, since it requires sickness, hospitalization, death, long term disability to achieve population coverage and works only until the next appreciably different variant or other infectious agent arrives. It's not yet horrific with the current strains of the flu or corona, but is a method of extinction with smallpox and was horrific with polio and Spanish flu. That's why the observation of pus from smallpox giving some immunity led to variolation and then vaccination.
The vaccines work better than is stated. The delta variant is more infective than early alpha strains [higher loads entering cells and replicating over time.] The alpha strain caused illness mostly in elderly >65, those with heart disease, diabetes, obesity, hypertension. But, little comparative disease in young people or kids. Death rates for people under 40 were <.02%. The delta is causing disease, hospitalization and death in young adults and kids similar to the alpha in the sicker older group, [since vast majority of older people were the ones vaccinated] . To gauge efficacy of the vaccine, one must compare effects of delta now with those of alpha on young adults in 2020. Ten to hundred fold increase in hospitalizations and deaths by delta. And, 97% of those now hospitalized are the unvaccinated, yet they are less than half the number of people vaccinated, further dramatizing how much vaccines work. So, to eschew the vaccine now is far worse than one might think.
Immunity from boosters appreciably enhances overall immunity [ part of why PFE MRNA were dual shots] even if not specific to the new variant, as mutations are rarely abruptly radical to leave vaccines completely ineffective. Immunity is also both "acute" with antibodies to various antigens, and "less acute" with T cells. The acute component is important to maintain short illness and lessen contagion and secondary spread. The mRNA vaccine boosted the acute response from 60% to 95% efficacy against illness going from 1 to 2 doses. That's why two doses were given. A 3rd booster will likely recover the interval loss of efficacy from time. Breakthroughs in the vaccinated will become rare again; the unvaccinated will once again be alone in the ICU.
The mandates will be significant. States and businesses will impose financial repercussions [already happening]. So will insurance companies not covering COVID costs [already happening]. Loss of work, penalties and costs for noncompliance, uncovered hospital bills, social isolation. AND the rage of the vaccinated heaped upon the recalcitrant unvaccinated losers will worsen as their medical costs, and national costs of delayed economic growth and inflation will become the burden now also borne by the vaccinated. DeSantis staking his career on wrong interpretations of a non peer reviewed study against the preponderance of the evidence is taking a career risk that will appeal to fewer and fewer people. When huge throngs of kids get sick and die, he will be but a historical footnote. People care about their kids, nit so much Afghanistan. We will see how that goes.