Here's a video that might help explain why black Americans are more affected by the Coronavirus: https://youtu.be/XAFD-0aMkwE.

It is a socioeconomic issue, at least in the US. I live in Minnesota (came across this post while scrolling through r/all). In Minnesota, there used to be racial covenants in communities in cities like Minneapolis that said people of color cannot buy homes. So, what would happen is black people either got pushed out of certain communities or white people would buy homes and black people who rent from them. Minnesota still has one of the lowest black homeownership rates in the US. These racial covenants were not only in the US, they were in states all over the nation. This would force black communities to have to stay together. Compound this with governments declaring areas with a higher population of black people as undesirable land, which allows industries that are more pollutant to move right in.

Black pregnant women are 4 times more likely to die than white women in the US. This is because, if you're a person of color, your pain is less likely to be taken seriously. (Hell, if you're a woman, your pain is less likely to be taken seriously.) People of color are 30%-40% less likely to receive pain medication than white people.

So, it's not just vitamin D levels. It's hundreds of years worth of inequality that is still going on.