Just to head this off from the start - the differential level of BAME COVID19 infection and severity (currently my understanding is higher both in UK and US) almost certainly does not have a strong influence from genetics.
It is poorly appreciated fact that self described ethnicity ("Afro-Caribbean", "White British", "African American", "European American") is only weakly linked to underlying human genetics, which is far far messier and complex than these ethnic group buckets.
(plus human genetics doesn't really work in a "bucket" or "label" way - it is more like a complex family tree, and a family tree that ultimately differs in different parts of your genome. We are all parts of all these family trees).
People are studying the host genetic components to COVID19 disease (covid19hg.org being one consortium); the expectation is that there will be some hits, probably some in the MHC region and elsewhere (polygenic in the parlance of genetics).
It will take at least another month I guess before the sample sizes are present to do the human genetic analysis, which ideally needs to be replicated in multiple locations. Some BAME cohorts are already present (British Asians one I know) but probably not enough
But - looping back to the original tweet - humans are a pretty genetically undiverse species and our genetics is still dominated by the original african population that exploded over the world some 300-200,000 years ago.
Ie, our genetic family trees across our genome merge worldwide pretty quickly (far faster than people realise), and then have relationships we *all* share due to our common origin as one species in Africa. Most common genetic variation between humans stem from this time in Africa
If we find robust genetic markers for COVID19 infection they are likely to be present or not across the world
(to add an extra complication, in the US and UK, many of the self identified ethnic groups - Hispanic, Afro-Carribbean, African-America, Black British in Liverpool - have substantial recent European genetic ancestry)
Journalists: *DO NOT* imply the difference in COVID19 infection or severity rates people observe between self identified ethnic groups are likely due to genetics.
A good phrasing would be "after the obvious large differences in comorbidities and socioeconomic status between ethnic groups, genetic effects which might have some effect between individuals are very unlikely to contribute to the average between group effects"
If you feel the need to speculate beyond this then... be warned that you are just making stuff up at that point :)
