Mythical Herd Immunity

David Spiegelhalter and Anthony Masters (Cambridge's Winton Centre and the Royal Statistical Society) have considered why levels of Covid-19 infections in the UK are so high, when 94% people have antibodies to the virus (https://www.theguardian.com/theobserver/commentisfree/2021/aug/14/will-we-reach-herd-immunity-for-the-new-coronavirus). Spiegelhalter and Masters agree with recent expert opinion that 'herd immunity' for Covid19 is 'mythical'. In theory, 86% of individuals having antibodies should have achieved it. Antibodies to Covid19, whether acquired by contracting the disease or by vaccination, do not, however, confer complete protection for an individual's life-time. Covid19 is different, in this respect, from measles. Vaccination against measles, gives something close to life-time protection (so-called 'sterilising immunity'). Spiegelhalter and Masters also point out that the claimed percentage of the UK population with antibodies to Sars-CoV-2 is somewhat misleading. Children and teenagers are not included in the totals. Spiegelhalter and Masters are also clear that contacts between people are very far from random. They confirm that Covid19 is likely to become 'endemic'. Endemic diseases, are always with us, and flare up periodically in poorly-resistant sections of communities (e.g. with low vaccination rates). Spiegelhalter and Masters opine, however, that getting as close as possible to 'herd immunity', would be of great benefit. It would reduce the Reproduction value (R) of the virus down to manageable levels. The R value is the number of people, someone carrying the virus, infects. For the initial Covid19 virus, R was around 3. That for the delta variant around 7. R needs to be much nearer 1. The whole thing could, of course, be imperilled with the 'realistic' arising of new vaccine-beating variants (https://www.theguardian.com/world/2021/aug/15/new-covid-variants-will-set-us-back-a-year-experts-warn-uk-government).