Here is a very good article with many points, here are two in particular that caught my attention:
People with a weakened immune system may give the virus this opportunity, as Gupta’s data show. More evidence comes from a paper published in The New England Journal of Medicine on 3 December that described an immunocompromised patient in Boston infected with SARS-CoV-2 for 154 days before he died. Again, the researchers found several mutations, including N501Y. “It suggests that you can get relatively large numbers of mutations happening over a relatively short period of time within an individual patient,” says William Hanage of the Harvard T.H. Chan School of Public Health, one of the authors. (In patients who are infected for a few days and then clear the virus, there simply is not enough time for this, he says.) When such patients are given antibody treatments for COVID-19 late in their disease course, there may already be so many variants present that one of them is resistant, Goldstein says.
These could impact the binding of the virus to human cells and also its recognition by the immune system, Farrar says. “These South African mutations I think are more worrying than the constellation of the British variant.” South African hospitals are already struggling, he adds. “We’ve always asked, ‘Why has sub-Saharan Africa escaped the pandemic to date?” Answers have focused on the relative youth of the population and the climate. “Maybe if you just increase transmission a bit, that is enough to get over these factors,” Farrar says.
Developing…the speed premium of course is rising…