Socio-economic factors do also matter: comments on the article "Can climatic factors explain the differences in COVID-19 incidence and severity across the spanish regions?: an ecological study".

A report published in this journal showed an inversely significant association between ultraviolet radiation (UVR) before the pandemic and cumulative COVID-19 cases in Spain. The analyses employed several meteorological factors, but socio-economic factors were not included. We examined the associations of COVID-19 cases with selected factors and found a significance on gross domestic product per capita (p = 0.037 by Spearman's correlation). Hence, simple regression analyses of UVR would be confounded with regional difference in economic activities. In addition, we raised several questions for limitations due to the study design and analyses.