[set fair (OP)]

anecdotal while obesity's link is characterised as a comobidity?

The data seems to be qualatively the same.
Quantatatively the evidence for a link with vitamin D deficiency is pretty big.
see:-
 Re: What accounts for the high degree of covid-19 gender bias?
« Reply #4 on: 06/05/2020 15:13:45 »

[Bored chemist]

OK, at least that's an interesting question.

How would you react is someone said that liposuction was a cure for covid?

[alancalverd]

Think of a beached whale. It will suffocate because in its normal environment most of its weight is supported by water so it doesn't need to shift much weight to breathe.

You can define obesity in terms of "flab to lung volume" ratio. If you are having difficulty breathing, the more flab you have to move to get your oxygen requirement, the less likely you are to keep your brain functioning. Supine, your diaphragm has to move a load of belly fat, and prone, your lungs have to lift your entire bulk to inhale.

COVID treatment is mostly mechanical - getting oxygen into the body by whatever means - so the comorbidity of obesity is fairly obvious to anesthetists, physiotherapists, respiratory physiologists  and intensive care nurses. It takes a special kind of curiosity to look for vitamin deficiency in someone who is having difficulty breathing: the link is not intuitive,  so the evidence is a bit slow in coming and rather more difficult to quantify.