Regarding this idea of "herd immunity", which looks to be what the government would really like to achieve and which I am not totally against.
These figures are aggregated from various studies. The idea is that if 60% of a population, mostly the fit and healthy, get an infection they will then be immune from further attacks and also passing it on. The other 40%, the old and infirm, would have to be isolated as best as can be done. Covid-19 is only a mild illness in those who are young, fit and healthy, so not such a bad theory - on paper.
In practice it would be hell.
In the UK some 40 million of us would have to catch Cov-19. Of them about 80% (32 million) would come out the other side virtually unscathed. Many, but not all, of the 8 million who become ill will need to be hospitalised with some needing critical care. 4% of those 8 million, or 320,000, would die.
It is a very big ask for any country to put its citizens through especially as the outcomes of other strategies are not known.
For the government's 80% then 53 million catch it, 42 million are mild, 11 million severe and 440,000 die. It is not going to fly and that's why all these sports and gatherings and festivals and museums and galleries are all doing their own thing.