I have been warning against the assumption of post-infection immunity, however I do not take the case as proven or unproven yet - particularly in an article that talks tosh like "Any virus that did this (
i.e. infect again) would be defying the laws of virology" , because it is not the case. (my addition for clarity in bracketed italics)
It is
LIKELY that infection would give
SOME immunity against
THE SAME STRAIN of the virus to survivors. However, that immunity may be in the form of lesser symptoms, rather than resistance to any infection, and it may be either temporary or permanent.... and that's without counting in any mutation of the virus, which RNA viruses do with ease. It is alo possible that this immunity will be different from one person to the next.
Do you see the problem about waiting for "herd immunity", yet? (apart from the pile of corpses that would accrue before it took effect) Truly, a little learning is a dangerous thing where these assumptions are concerned.