i got pig flu when it was around a few years back.
at the time they were handing out pre-prepared packs of some anti-viral drug (which in my experience made a big difference in a couple of days) from local emergency dispensaries, you were not supposed to go to a doctor's surgery or a high street pharmacy in case you passed the infection on. my local one was in an out-of-town unit away from shops and offices.
As well as all the usual flu-like symptoms, the key to the diagnosis was a substantial increase in body temperature, quite sudden, came on overnight. I can't remember now how much it was, might have shot up two and a half degrees.
I recall at the time, a lot of older people, who usually are at greater risk from flu, didn't get it because they had immunity from a similar strain that was around 50 or 60 years ago.
There's always flu around, it comes back every year in a mutated form that a lot of people aren't already immune to. If you're a person who's offered the jab it's well worth having.