I would like to add a couple of comments here.
A first question I always ask is the following: is herd immunity achievable at all? Where are the proofs that someone infected will be safe from being re-infected later? I have not seen anything with this respect (maybe we will just have to live with the virus and that’s it). Therefore, it is important to keep in mind that herd immunity may never be reached. This being said, I am not an epidemiologist. So feel free to redirect me to anything that I could read to be better informed.
Also, another remark concerning the lock-down: the only motivation behind it, still according to my own personal opinion, is related to the capacity of the hospitals. The two ways to prevent the ICU units from being overwhelmed are either to limit he incoming flux, or raise the bar. Lock-downs address the former (and this is why they have been put in place) and bad health politics have made the bar so low today (and this does not seem to change unfortunately).
Very nice post my the way!