Ha, good luck finding Vitamin D en masse... however, I do have a treat for you (Israeli study too!):
https://www.medrxiv.org/content/10.1101/2021.06.04.21258358v1.full.pdf

The TL;DR of it is this:

So long as your Vit-D is above 20, you're a lot more protected.

HOWEVER:

Vitamin D deficiency was associated with ...
comorbidities including COPD (Chronic obstructive pulmonary disease) (p=0.006),
diabetes (p=0.026),
and hypertension (p =0.016)

In other words, people with low Vit-D levels were fucked to begin with.
The optimist in me wants to believe that low Vit-D levels are responsible for general system vulnerability - the easy solution then, is to get more Vit-D.
The scientist/realist in me understands that most likely, we're talking about people with an unhealthy background, which expresses itself in many ways, including low Vit-D.