It's bee extensively, directly tested by randomised controlled trials using vitamin supplements and no effect was found: https://www.health.harvard.edu/blog/do

It's bee extensively, directly tested by randomised controlled trials using vitamin supplements and no effect was found: https://www.health.harvard.edu/blog/do-vitamin-d-zinc-and-other-supplements-help-prevent-covid-19-or-hasten-healing-2021040522310 https://www.health.harvard.edu/blog/do-vitamin-d-zinc-and-ot... "The researchers found that people receiving the supplements, whether individually or combined, had no improvement in symptoms or a faster recovery when compared with otherwise similar patients receiving neither supplement." Also it's just an absurd fantasy to say that 'they' are stopping people taking supplements or being tested. "Despite questions about the overall benefit of these supplements, many doctors began prescribing them routinely in the early days of the COVID-19 pandemic..." So some doctors have been doing this and all the options have been explored, and the kind of evidence you'd need to push this at the population level just isn't there. Look, the information is out there, these supplements are available, you can get tested for deficiencies any time you like, go for it. There is no conspiracy, it's just that overall many medical professionals feel that this has been studies and they just don't agree with you that this is a significant factor, that's all. Why do you think they disagree, if not a genuine difference of opinion? What's the alternative narrative? The entire medical profession across many disciplines and diverse political opinions and different nationalities is united against humanity?