It predates the pandemic. The first studies suggesting "maybe we are all D3 deficient" go back over a decade, and so articles about it have popped up on HN a fe

It predates the pandemic. The first studies suggesting "maybe we are all D3 deficient" go back over a decade, and so articles about it have popped up on HN a few times a year. Then add the pandemic and the new implication that it affects COVID outcomes and you start to get a hype cycle. I will say that I find some value in D3 supplements personally and have used them, at varying levels, since 2009. But like most health issues, its impact can't be reduced down to a one-factor analysis, and often entails discussion of other supplements and deficiencies.