I think, you have explained herd immunity developed naturally by pandemic and manipulated by vaccination very well in detail. Yes it does happen. Here,my concern still is, whether such immunity is acquired by developing B Cell immunological memory or by actual presence of antibodies? Some big path lab people told me " Generally, IgG antibodies remain present in the body for several months to years after an infection for long-term protection against the offending microorganism. Pre-formed, circulating IgG antibodies are ready to attack when re-exposed to the microorganism resulting in infection prevention or a quicker immune response with less severe symptoms." However I have a say in it:- that long term IgG antibodies persistence in the body is meant for a purpose to deal with some chronic or latent state of Covid Virus persisting in the body post acute infection treatment(may also be some traces of injected vaccine)? I am not sure presence of these antibodies for prolonged time in anticipation of any future offending microorganism is physiological or not because if any such offending microbe will infect in future Memory B Cells can instantly secrete desired antibodies to handle that infection.Then what is the need of unnecessary maintaining antibodies by body for 6 months or so unless some infection or its traces still exist post infection for long term against which consistent antibody meadiated immune response is necessary. It made me to think about possibility of its chronic or latent stage.