Immunocompromised are also more likely to be infected with multiple strains at the same time, and for there to be recombination between these, possibly leading to new variants.

NEJM article also talked about there being multiple mutations found in immunocompromised, given the same strain sticks around so long in the host it mutates, then if that mutant has a survival advantage it also sticks around long enough (since immunocompromised can't clear the infection) to have another mutation on top of that, again and again.

So, an immunocompromised patient could provide selection pressure for a more virulent virus with many mutations, which eventually then is spread to the rest of the population once the super virus forms in an immunocompromised patient - a new super mutant variant.

Of course these multiple mutations and recombination events could happen in a non-immunocompromised population, it would probably just take a lot longer to do so.

The above is all somewhat theoretical, but agree that the immunocompromised seem to be a special breeding ground for super mutants.


In any event, despite my optimism about delta waning soon in the US like it did in India (2 months to peak, 2 months to end of the delta wave) and started to do in UK (2 months to peak and start down, but after 2 weeks tick up again), it appears that delta may not go away so easily after all, and there are likely to be more variants spreading worldwide since on a population level, persistence of the virus in 3rd world countries with low vaccination rates and with some chronic immunocompromised people will likely continue to produce new variants that will likely be less susceptible to protection from current vaccines.

In short, we will need treatments like leronlimab for quite a while.