A meta study of papers on effectiveness concluded an overall effectiveness of 15% ranging from 50% effective up to age 65, then diminishing thereafter even below 15% in very old with comorbidity. Indeed the most at risk group do not get vaccinated as their immune systems would not cope. And more important, unlike measles, polio, mumps, etc, ‘flu vaccine do not give lifetime protection.
It is well recognised that many people suffer Colds and ‘flu symptoms within the two weeks of vaccination. So they get a bout of disease they might not otherwise have had. The less serious claim is one of those claims it is impossible either to prove or falsify, as there can be no way to know how an individual would have responded without the vaccine.
The problem with ‘flu vaccines is every year they have to be changed usually based on new ‘flu mutants circulating in the Southern Hemisphere during their Winter, our Summer. Some years a different mutant strikes in the North than the one(s) the vaccine makers had anticipated making their vaccine useless.
However it is still the case, you cannot be vaccinated against influenza (the disease), just one of the viruses causing it. Since the number of circulating ‘flu viruses is enormous, being protected against one does not mean another one will not get you, or a coronavirus, rhinovirus, etc.
But influenza - unlike SARS CoV 2 - can be very serious and fatal among the young and healthy, particularly babies and infants. Isn’t it strange then, given the manic rush to vaccinate the young against SARS CoV 2 from which the risk to the young is approaching zero, that in previous times there has never been such zeal to vaccinate the young against ‘flu virus, which at least would make some sense as it is more effective among young? Fatalities during the 1917 Spanish ‘flu epidemic were mostly among the young.
And then there is the pneumonia virus. I’ll bet you didn’t know there was a vaccine against that… a very serious virus. I didn’t know until last year until my sister mentioned she had had the vaccination in the 1980s. It gives lifetime immunity, so just one dose per person and is long off patent so no money in it for Big Pharma. Could that be why we never about it I wonder, or am I just being cynical?