Also worth mentioning that several research studies in the last 10 years have concluded the original recommendations miscalculated the RDA for vitamin D and were off by a factor of 10.

https://www.sciencedaily.com/releases/2015/03/150317122458.htm

Alsof worth mentioning that the link netwerk vitamine D and health has been established many times. In Covid as Well. Yet taking vit D tablets has bever been proven helpfull. People with high vit D levels go out more exercise more have a healthy gut biome... Taking Vit D may be useful but it is not the magical answer to everything