Sourced of - J J Couey / Gigaohm Biological - https://vimeo.com/559167685 Here is a quick summary of why our immune memory is different for different viruses. It all comes down to the number of good targets available for the immune system to remember. The bottom line is that our immune responses are different for different viruses, and this is built in. There is no equivalence between immunity to Measles and immunity to coronaviruses.