Exactly the same as flu or the common cold then!
No big deal.
There is only a limited number of flu variants that they decide upon each year. Which one shall we release this year?
In other words, which vaccine have we got too may of and need to shift
It's very difficult to catch "full" flu. I've only had it twice in 50 years, and most certainly don't recommend it.
But remember, we never hid from it at all, like never!
No extra hand washing, no distancing and no mask wearing, it was always a hand up and a polite "Don't give me your cold please".
There are something like 200 viruses that give similar symptoms of the common cold, that's why we've never been able to pin that down to sort "it" out, because you never know which version you've got.
Read an interesting article yesterday that explained that the Spanish Flu never went away, it just went dormant. It basically said that every person who has had the flu ever since then up to now has had a mutated version of that same virus.