Earlier quoted context omitted.
It's not "nonsense". It's real. It works for almost every other virus out there (even colds and flu, even though it's imperfect: new seasonal cold and flu strains don't become pandemics, because many people have some immunity from previous infections). If you let a large enough fraction of the UK contract and recover from COVID-19, we have every reason to suspect that the society will develop good enough herd immunit…
3. the immunity gained through an infection holds for a long enough time (how long would need to be checked with the infection rate), which we do not know yet Additionally, we know nothing of the long term effects even for the "young and healthy". Mortality rates for people 10-39 is 0.2%, 40-49 it's at 0.4%, 50-59 1.3%, 60-69 at 3.6%. Serious conditions develop in a bigger proportion of cases, so you are looking at 4…
According to https://www.statista.com/statistics/281174/uk-population-by-...
8.96 million aged 50-59, 7.07 million aged 60-69.