Your 'of its kind' phrasing does all the work, and it's not justified. Plenty of viruses don't create useful immunity, from flu to AIDS to the other seasonal co

Your 'of its kind' phrasing does all the work, and it's not justified. Plenty of viruses don't create useful immunity, from flu to AIDS to the other seasonal coronaviruses, where immunity length is in the order of a few months...