Pandemics causing death are linked with increases in support for radical political movements, all the way back to the 1918 flu pandemic and the birth of 20th century fascism
Evidence linking past experiences of worsening health with support for radical political views has generated concerns about the consequences of the COVID-19 pandemic. The influenza pandemic that began in 1918 had a devastating health impact: 4.1 million ...
Something not considered in this paper, Post Viral Syndromes, may also be a factor. Though some acknowledgement of post viral syndromes dates to at least the 1950's, it's only with the COVID19 pandemic that modern medicine has really begun to take a look at this with some seriousness. These PVS's can affect many organs in the body, specifically the nervous system, and including cognition.