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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 mean

by kdelok 9y ago

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.

dominotw 9y ago
> CDC reckoned they reduce the risk by about 40-60%. curious, Do you have a link to this by any chance? According to this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693492/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693492/ 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. According to this CDC study https://academic.oup.com/cid/article/64/5/544/2758477 https://academic.oup.com/cid/article/64/5/544/2758477 "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. Just to quote one, http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136539 http://journals.plos.org/plosone/article?id=10.1371/journal.... "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."
- bonzini 9y ago
  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.
  - dominotw 9y ago
    > However, flu vaccine isn't useful to the general population. CDC makes no such distinctions in USA. https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html Any references to your claims?
    - bonzini 9y ago
      Italian only, but see item 11 of http://www.salute.gov.it/portale/p5_1_2.jsp?id=103 http://www.salute.gov.it/portale/p5_1_2.jsp?id=103 - should be easy for Google to translate it. Though I should have written "isn't _equally_ useful to everyone in the general population".
- moccachino 9y ago
  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.
- PeterStuer 9y ago
  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.

by kdelok 9y ago

dominotw 9y ago

> CDC reckoned they reduce the risk by about 40-60%. curious, Do you have a link to this by any chance? According to this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693492/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693492/ 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. According to this CDC study https://academic.oup.com/cid/article/64/5/544/2758477 https://academic.oup.com/cid/article/64/5/544/2758477 "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. Just to quote one, http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136539 http://journals.plos.org/plosone/article?id=10.1371/journal.... "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."

bonzini 9y ago
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.
- dominotw 9y ago
  > However, flu vaccine isn't useful to the general population. CDC makes no such distinctions in USA. https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html Any references to your claims?
  - bonzini 9y ago
    Italian only, but see item 11 of http://www.salute.gov.it/portale/p5_1_2.jsp?id=103 http://www.salute.gov.it/portale/p5_1_2.jsp?id=103 - should be easy for Google to translate it. Though I should have written "isn't _equally_ useful to everyone in the general population".
moccachino 9y ago
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.
PeterStuer 9y ago
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.