I saw some people losing their heads a bit about the fact that the flu shot has been announced as less than 50% effective this year (though in fact, if you dig into the numbers, it depends on your age group — in children it’s been 61% effective, but much, much lower in older adults). So to clarify on the urgent burning question: no, it doesn’t mean that this is some superbug that’s going to sweep the world and kill most of civilisation. What it means is really just… the scientists guessed wrong.
In the end, what goes into the flu shot that’s distributed to vulnerable people is based on educated guesses. What flu strains are going to be important, prevalent, worth protecting against? And they have to make this guess in advance, before the shot is actually needed — or it could never be produced and distributed in time.
Moreover, even though the flu shot isn’t preventing people catching influenza, it is softening the impact for those who have been vaccinated. They have fewer severe symptoms and recover faster. So it’s not totally useless, either.
In conclusion: it’s not the end of the world. It’s just like the weather forecast: sometimes it’s pretty accurate, and sometimes something just disturbs all the predictions, throws everything off, and produces an unexpected result.