The variants — and their uncertain effect on immunity (natural or vaccine-induced) mean that herd immunity is not that helpful of a concept to track.
What matters are the data on infection rate.
What matters are the data on infection rate.
Relying on the infection rate with these unknowns is unreliable. Reminds me in the middle ages to find out who is a witch or not. They thought of themselves highly scientific and rational those times. Better burn some more witches than letting some escape.