The name is a pun on the false equivalency that Covid-19 is less dangerous than it actually is, as "flu" is colloquially used to signify that an illness is sub-acute and ubiquitous.
The film counts as an example of the psychological phenomenon of "Extreme Overvalued Beliefs" in which an individual is exposed a minority held belief present in their society.
The belief is usually inaccurately referred to as a "conspiracy theory."
The individual begins to search and obsess over the perception of evidence for a pseudo narrative. In the absence of perceived counter evidence the individual progressively searches for more extreme information and becomes interwoven with a like minded group of other individuals who share even more radicalized details and blogs. They reassure each other of the validity of the belief and eliminate any source that contends otherwise.
In the final stage the individual is no longer content with letting the majority of society to be "enslaved" as they once were and uses dialogue at first but will eventually legitimize the use of force to divorce others from the majority endorsed accurate reality.