It shows a complete lack of understanding of what a 'virus' is.My brother in law has just tested positive for the second time. I didn't know hen's teeth were so common.
Virus's mutate, hence Delta,Omicron and onwards for the virus Covid-19, and different flu shots per year for the flu virus.
The amount of people who have had the flu more than once is certainly not in the 'hen's teeth' range of numbers.
If you don't believe that virus's (any type) are a thing, yes incredibly there is a whole subset of conspiracy nuts who follow https://en.wikipedia.org/wiki/Germ_theory_denialism