[its-summertime]

From what I can tell, the "ecological integrative approach" is referring to the approach used in the research of that paper, not on how Vitamin D acts in relation to COVID

> Following an ecological integrative approach, we examined the associations between published representative and standardized European population vitamin D data and the Worldometer COVID-19 data at two completely different time points of the first wave of this pandemic.

and

> Thus, a major limitation of our ecological approach is that we had to rely on published - but perhaps not always completely representative - data on the vitamin D status of the populations in Europe.

[gmane]

Right, I was criticizing the approach. Edit: specifically the fact that the paper has no discussion of how the meta-analysis data was prepared, processed, or how they made sure it was complete.