Not all flus are made equal, and the data about which flus are particularly deadly lags reality. If a flu as deadly as the Spanish Flu emerged again, you would be wise to worry about it. But until then? Until then, I suggest you go about your life.

We started wearing masks because covid actually existed, not because we feared that it might one day exist. Fear of hypothetical future covid strains is an example of the later, not the former. I'll consider fearing them once they actually exist, just like those hypothetical future flu strains.