Most of the evidence that vitamin D seems to be beneficial is not from controlled trials, therefore NICE wont pay as much attention to it. That is because of things like thalidomide happening in the best, they want good quality research before recommending it. There are larger trials going on but not completed. Clinical trials are often slow to enroll people and to write up.
There is a considerable difference between saying those with low levels of vitamin D do badly and supplementation will change that and be safe. Most scientists would agree with the first, be more dubious about the second.
This is absolute nonsense. Vitamin D is not some new, untested drug. It is actually a hormone which is developed naturally, and completely harmless, even in huge doses. There is absolutely no risk in prescribing calcifediol in doses of 20,000 iu, for people who are already infected, which is what all the highly successful trials are doing. Instead, NICE recommends 400iu, which is ridiculous.
And yes, there are scores and scores of studies on its almost miraculous effect when given to covid patients: things like a 96% reduction of ICU intake. This is being kept from the public.
Since it is really harmless even in high doses, wouldn't it be of benefit to prescribe it anyway, as was done in AndalucÃa, with spectacular results? Or would that make the whole rush to vaccines look silly? Think about it.
The AndalucÃa doctors concluded that a trial would be a waste of time and involve far too much burocracy and paperwork and organisation, so they just went ahead, gave the patients high calcifediol doses, and look what happened! A miracle.