Do the molecular structure of spike protein of any seasonal flue change based on temperature? As I understand it, we don't fully understand why seasonal flu is

Do the molecular structure of spike protein of any seasonal flue change based on temperature? As I understand it, we don't fully understand why seasonal flu is seasonal. The popular suspects are: A change in behavior of people. The decline in the amount of ultraviolet radiation (that damage or kills the virus). That drier air lowers the body defense against respiratory virus infections. That decomposition rate of viruses occur slower in lower temperatures. And finally the lover levels of vitamin D in colder climates. Does this study provide any evidence in regard to any of those theories?