Why COVID-19 Herd Immunity not working for UK Europe and USA and recover and cure for Coronavirus

This video talks about
– The concept of herd immunity
-Why UK, and USA were wrong at first thinking it’s just another flu and should just let everyone get it and get herd immunity
-Different ways herd immunity can be achieved
-Why it does not work for COVID-19
-What else can we do ?
-Why people are asked to keep a social distance or even self isolate