Both Omicron and Monkeypox show evidence of mutation by the human immune system
The human immune system can mutate viruses in a particular way- leaving a signature in the RNA or DNA
Suspect that most of the time the human-caused mutation results in the killing of the virus
Unfortunately, very rarely, it will improve the virus: making it more infectious
In the case of Monkeypox, it seems that the human-induced mutation callows it to spread between humans
Scientists Zero In on Origins of the Monkeypox Outbreak - New York Times - June 23, 2022
(for Monkeypox) "Of the 47 mutations identified in one analysis, 42 carry the distinct signature of an enzyme called Apobec3. This enzyme, first discovered by researchers studying H.I.V., is a so-called host defense factor — an immune-system weapon that animals and people use to disarm viruses like monkeypox."
"Some experts have cautioned for years that the eradication of smallpox in 1980 left the world vulnerable to the broader family of poxviruses and raised the odds of monkeypox evolving into a successful human pathogen."
Footprint of the host restriction factors APOBEC3 on the genome of human viruses - Aug 2020
" We demonstrate that the APOBEC3 selection pressure impacts at least 22% of all currently annotated human viral species"