Learn the definition first.
Then think about what happens when you change behavior or change the disease.
Singapore's recent case rates are completely consistent with a place which was herd immune, then experienced a change to R.
It definitely is not proof that herd immunity is somehow impossible.
Definitions. Plural. Espola's in particular is technically correct also but very cute.
You are proposing a floating one keyed to your old favorite R. 1. That's not what Fauci's definition means (his was keyed to zero COVID though he has since revised it as in the interview outlined about, 2. if it's keyed to behavior it's not herd immunity...any definition to obtain general acceptance requires going back to pre-COVID, not a new normal however much of a paradise that new normal is for people like how., 3. It's not proof...I still think it might be possible with natural immunity but I'm open to Dr. John's idea that it's not....but it's a damn good evidence that masks + vaccination doesn't get us there.