Where Did Omicron Come From?

Manon Ragonnet-Cronin (an MRC Research Fellow at Imperial College London) suggests that the Covid19 Omicron variant is towards the far end of a long series of mutations. He goes on to float the 'runners and riders' explanations of how the variant originated (https://www.theguardian.com/commentisfree/2021/dec/22/omicron-scientists-variant-virus-lab-public-health). One view is that Omicron originated in a part of the world (not necessarily South Africa?) that does little or no genetic sequencing. It could have gone undetected for some time. A second possibility is, that humans infected another animal species. We know that dogs, cats and mink are highly susceptible. The mutations could have occurred in that animal, before the virus was passed back to humans. Ragonnet-Cronin thinks the third possibility is the most likely. In this scenario, an immunocompromised individual (with AIDS or being treated for cancer) is infected by Covid19. In such a host, the virus could accumulate mutations, without challenge by the immune system. This has already been advocated as a possible explanation of the origin of the alpha variant. It's clear that all three are real possibilities. We consequently need a) more sequencing, in all parts of the globe; b) careful monitoring of situations where Sars-CoV-2 jumps to other species (there is already a long list of domestic and zoo animals) and c) particular care, when dealing with immunocompromised folk. So long as the virus has available hosts, it can mutate. The virus doesn't plan but its highly efficient replication, makes the most of any opportunity left to it by humans.