So NY has now finally slowed down, even though the rest of the country is blowing up.
Some people are asking when herd immunity will be reached. The basic formula for figuring out the percentage that needs to be infected to reach herd immunity is (1 – 1/R∅). This means that if the R∅ is 2, then you need (1 – 1/2) or 50% immunity. But what is the R∅ of SARS-CoV-2? It varies.
It depends not only on the innate infectious nature of the virus (which, in this case, appears to be on the higher side, given the rate of asymptomatic carriage), but also on the actions of people. If everyone distances themselves from each other, then it would essentially go to 0. Wearing a mask should also help reduce it.
Are we going to keep the infections at zero forever in NY? No, there are going to be recurrences. But I think if we all wear masks, wash our hands, and act in a reasonable manner, we can prevent excessive cases to a large degree.
Whether everyone is going to do that is the ultimate question.