Flu vaccines probably don’t do much harm and may do some good, but they’re not fool proof. They’re based on a projection of the next year’s flu season, since flu viruses mutate and every year is different. That said, if you do get any flu, that year’s flu vaccine probably lessens the severity.
However, to my knowledge, they didn’t have anything very effective against swine flu, which had a major outbreak a few years ago. Swine Flu is extremely dangerous, not only for its possible follow up infections but in itself, and was noted for being extremely dangerous to young, healthy people.
It comes from China. Not accusing China of having poisoned this young woman, simply saying that we should be on alert for this virus if it’s reappearing.
The 2018-19 vaccine includes anti-H1V1—i.e., anti-”swine flu”.
https://www.cdc.gov/flu/about/season/flu-season-2018-2019.htm
Whether one gets the vaccine or not is usually a function of whether their healthcare provider pesters one to get it. (Some of course go to a drugstore and get it before their healthcare provider’s notices kick in.)
This year, we were pestered a lot!! A busy 26-year-old may not have been subject to the same pressure!