In the case of people of African descent, I think we _do_ have a specific candidate for a biological difference affecting COVID-19 outcomes. A randomized clinical trial found that
+"Autumn COVID-19 surge dates in Europe correlated to latitudes, not to temperature-humidity, pointing to vitamin D as contributing factor"
+https://www.nature.com/articles/s41598-021-81419-w
+
https://www.sciencedirect.com/science/article/pii/S0960076020302764
https://pubmed.ncbi.nlm.nih.gov/16549493/
https://en.wikipedia.org/wiki/Scientific_racism
+https://www.bmj.com/content/371/bmj.m3872/rr-5
+
[racialists get annoyed that people use "skin color" as a metonym for "race", but in this case, we actually are talking about skin color!]
https://en.wikipedia.org/wiki/Causal_graph