So, um, no, we are nowhere near the 50 percent, at least according to any data we might have. And, depending which expert do you heed and what is the definition of "herd immunity" they're after, we need 70%, 90% or 95% before this is over.
50-66% is most likely, and perhaps less. Estimates of R0 are mostly in the range of 2.0-2.5.
50% would lower a 2.0 R0 to 1.0. 66% would lower a 2.5 R0 to 1.0. And this ignores that we may have permanently changed behaviors (e.g. handshakes) that facilitate spread, so we may not even need this fraction to curb tramission.
New York City is presently somewhere past 23%, so that's a big chunk of the way to a 1.0 Rt without controls.
https://www.bloomberg.com/opinion/articles/2020-04-24/corona... "in the most severely affected regions only about 10% to 15% of the population had been infected"
So, um, no, we are nowhere near the 50 percent, at least according to any data we might have. And, depending which expert do you heed and what is the definition of "herd immunity" they're after, we need 70%, 90% or 95% before this is over.