A researcher tested recovered SARS patients who became ill and recovered in 2003 with SARS (COV1) again in 2021. They were still immune, after 17 or so years.
The same researcher tested those same recovered SARS patients with COV2 (Covid). They were immune to it because the viruses were not different enough, still recognizable to the immune system.
We don’t have to have exact matches to get major (complete) or partial immunity. Most of us already had related coronaviruses so we had some or complete immunity from Covid.
The CDC lied and said COvid was 100% new, and that none of us had protective prior exposure (they classified it as “novel”) in order to enact their lockdown, economic destruction plans.
Basically we’ve been lied to on a number of issues - for example, I doubt we ever needed annual flu ‘vaccines’.
So they create the impression that one illness from a coronavirus won’t impact another (immunity) which is not true.
So the theory is that Omnicron will safely trigger and train an immune response in those who have no prior exposure to Covid (not a large percentage anymore) and then the herd will have predictable immunity, with only the immune compromised in need of careful treatment/attention.
A group on FreeRepublic had been tracking SARS in 2003. It appears the binding affinity was strongest in Chinese. People in North America showed about a 1/3 level of binding affinity. A small group with ancestry back to the Black Plague survivors had 0% binding affinity.