Wow, this person is really claiming that NYC was "herd immune by May 1st".

Even the articles cited to try and make these claims are saying something completely different. The "article" states-

> MIT’s news publication, The Tech, now seems confident that immunity is happening

Yet if you actually read what The Tech wrote it's very clearly not saying that-

> “It seems there is the ‘herd immunity is already reached’ team and the ‘we are all going to die’ team. The good thing is, that there is a third ‘let’s get the data and let’s look at what this all means team’ out there,” tweeted Florian Krammer, an immunologist at the Icahn School of Medicine in New York City.

The article also makes a distinction between "herd immunity" (where the entire herd is immune because there aren't enough people susceptible to the disease to transmit it) and "population immunity" (where there is enough immunity to slow- but not stop- the spread). The author completely ignores this distinction to try and make it look like The Tech was saying something they didn't.

"A few months ago I said “let’s do a science experiment- if NY has herd immunity cases won’t go up with reopening”. Well here are the results- NY, not going up. There really is no other explanation I can think of for this besides herd immunity."

Now that's Real Science™.

I see no actual argument that her immunity is occurring, just a declaration and pointing to cases waning.

Couldn't there be other explanations for waning cases?

Careful with this one. He's really stretching a lot of facts here. 3% infection -> immunity isn't insane but it's not something that can be relied upon and it's way too early to be sure this is the end. We're still seeing repeat infections as well.

It is dangerous to say this at this point. People who have an agenda will use this to say that it is now safe to resume business as usual. IT IS NOT!

This is fairly expected and also happening in large parts of Europe.

One thing I found interesting that is initially a bit counterintuitive, but makes a lot of sense in hindsight, is that the herd-immunity thresholds change based on the infection vector (i.e. natural spread vs. random vaccination): https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v...