Interesting because of meta-analyses concluding the opposite about URIs at least, if not COVID per se.

One thing to note is that period of time of the trial was very weird with regard to non-COVID URIs, so the results might be influenced by that. Not to dismiss them, but there might be something to be learned potentially with the types of URIs.

Or vitamin D just has no effect on URIs.

This is important research to get the definitive answer, but I'm not surprised. https://news.ycombinator.com/item?id=23120719

35,000 subject test in Norway, double blind, Fish Oil. So tested D, A and Omega-3.