I read an article that perhaps explained why. I tried to find this article to share here but I couldn't. I read it a couple of years ago. This article made much more sense.
The article noted that higher illness and death rates occurred in more rural areas due to a number of factors, the most significant factor being lack of access to adequate healthcare. Additionally, mask and vaccines were made more readily available in urban areas due to their high density populations, as they should have been. Those high density population centers were also prone to initiate mandates as compared to rural farming and ranching communities with very low densities.
The connection to politics and parties was really only because higher density population centers tend to be more democrat than republican.