Flu vaccines aren't useless, but they also aren't 100% effective. The CDC reckoned they reduce the risk by about 40-60%.
Flu is a variable pathogen, which means that it evolves to look different from an immune perspective over time. It follows clustered patterns, where the flu strain will look pretty similar (and vaccines will be more effective), then it "jumps" to a new cluster every few years or so (and the vaccines will likely be less effective). There's a whole bunch of work goes into predicting what flu strains make most sense to use for the vaccine in a given flu season.
After looking at "328 households with 1441 members, including 839 children," for an entire year (2011) these authors determined that there was a difference of 4/10ths of one percentage point between those who received flu vaccine and those who didn't.
The infection risk was 8.5% in the vaccinated and 8.9% in the unvaccinated.
"We observed decreasing vaccine effectiveness with increasing time. Maximum vaccine effectiveness was observed shortly after vaccination, followed by a decline..... Vaccine effectiveness remained greater than zero for at least six months for influenza A(H1N1) and influenza B and at least five months for influenza A(H3N2) viruses."
They say "greater than zero" , far cry from 40- 60% :D
Cannot post more replies atm, but for people saying 5% is still something.
> Going from 8.9% to 8.5% is a 5% reduction in flu cases. If this translates to 5% fewer sick days during the flu-period and a 5% reduction in doctor visits that are due to flu symptoms (some people go to the doctor for everything), that can absolutely be a reason for the government to want people to get their flu shots.
This line of reasoning assumes that there are only positive effects from vaccines. There are many many side effects of flu vaccines.
"Hospitalizations were slightly more common among subjects who were vaccinated than among the others"
"hospitalizations for pneumonia and influenza, that were 47% more likely among subjects who received the tetravalent vaccine as compared with those who were not vaccinated."
That's a 0.4/8.9 reduction, about 5%. However, flu vaccine isn't useful to the general population. In many countries is usually administered to people that are most likely to develop complications such as pulmonitis.
> > Going from 8.9% to 8.5% is a 5% reduction in flu cases. If this translates to 5% fewer sick days during the flu-period and a 5% reduction in doctor visits that are due to flu symptoms (some people go to the doctor for everything), that can absolutely be a reason for the government to want people to get their flu shots.
> This line of reasoning assumes that there are only positive effects from vaccines. There are many many side effects of flu vaccines.
----
This is why I also said:
>So assuming that the flu vaccine is harmless and the cost is not too great, it can make sense to get it even if the effectiveness rate is low.
As far as I remember flu vaccines work by looking at the origins of the yearly epidemic (in the east, typically china etc.), predicting which strains will become the dominant ones and then starting to cultivate neutered forms of those (in eggs) on a mass scale to have the vaccines ready by the time the epidemic hits 'the west'. Some years the predictions of the strain are wrong and the vaccines less useful as most people will get another strain.
They do strain selection twice a year (once for northern, once for southern hemisphere). The years where they get it wrong are usually the years where the strain jumps between different clusters.
That is for 2011. The effectiveness of the vaccine is different every year. Some years it gets close to 80% (from memory and probably wrong), some years it is only 10%. The average across all years tends to be 40%.
Going from 8.9% to 8.5% is a 5% reduction in flu cases. If this translates to 5% fewer sick days during the flu-period and a 5% reduction in doctor visits that are due to flu symptoms (some people go to the doctor for everything), that can absolutely be a reason for the government to want people to get their flu shots.
Personally I have never had a flu shot and am not inclined to start doing so, but I know people who have and according to them, if they do get the flu it affects them less in the years they get their shots vs. when they don't.
So assuming that the flu vaccine is harmless and the cost is not too great, it can make sense to get it even if the effectiveness rate is low.
I almost wonder, in my more cynical moments, if "flu shots" are people just paying to get poked with a couple of cc's of saline, for all the effectiveness it seems to provide.
I find the way that response has been worded to be misleading. Labeling an effectiveness of around 5% as 4/10ths of a percentage demonstrates a desire to mislead the reader.
Most people will shake off a flu infection easily. The elderly or people with other medical problem may not, so I find it a weak argument to say they are useless based on that study.
The second study quoted is pretty much what I would expect based on my knowledge of influenza virus. It evolves quickly, which is why being exposed to it once year doesn't build up your immunity to the evolved strain going around a year later
What about flu vaccines? Even govt runs ads urging people to get their flu shots, even though they have been shown to be useless.