It was found that immunologically active memory cells declined quite rapidly after the vaccination, but eventually the number of cells plateaued at about 10% of the original number.
Now there is at least one scientific report showing that these cells remain for more than 50 years and are able to provide an active immune response when challenged (by experimental revaccination). Thus, it appears that people who were vaccinated against smallpox still retain protection against the disease, and therefore at least some (but not complete) protection against monkeypox virus.
Ref: Crotty S. et al. Cutting edge: long-term B cell memory in humans after smallpox vaccination. J Immunol 15;171(10): 4969-4973.
https://pubmed.ncbi.nlm.nih.gov/14607890/
Hey! Great info. Thank you.
And no SADS killing tens of thousands of healthy people either.