# What if everyone got the flu vaccine? **URL:** \ **Category:** Factual Questions\ **Created:** [December 9, 2019, 12:39pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589 "2019-12-09T12:39:25Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [December 9, 2019, 12:39pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/1 "2019-12-09T12:39:25Z")
According to [the CDC,](https://www.cdc.gov/flu/fluvaxview/coverage-1819estimates.htm) here in the US about 60% of kids and 45% of adults get the flu vaccine. [The results?](https://www.cdc.gov/flu/about/burden/index.html) About 21M people still end up catching the flu, with about 50% of them visiting a doctor for treatment - and about 15% of them actually ending up hospitalized. In any given year, 12,000-61,000 people die. I didn’t see how many sick days are attributed to the flu every year, but it’s fair to add that loss of productivity to the total burden of health care costs, misery, and death due to the flu. No vaccine is 100% effective, and in some years health officials make incorrect predictions about which strains of flu will be most prevalent and end up preparing a vaccine with unusually poor effectiveness. Under these circumstances [herd immunity matters,](https://en.wikipedia.org/wiki/Herd_immunity) and with flu vaccination rates hovering around the 50% mark, it seems we don’t have it. But what if we did? What if everyone in the US got the flu vaccine each year? Does the CDC (or anyone else) publish estimates of what could be achieved, in terms of public health, if flu vaccination were universal? How many illnesses, sick days, hospitalizations, and deaths would we have under such circumstances? ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [December 9, 2019, 1:43pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/2 "2019-12-09T13:43:37Z")
A full explanation of the modeling for herd immunity in general is [here](https://www.oerafrica.org/FTPFolder/Website%20Materials/Health/OER%20Sampler/Univ%20Botswana%20Medical%20School/resources/John%20Hopkins%20BSPH/EID_lec4_Aron.pdf) but you need to know R (the reproduction rate which is the number of secondary cases per new case introduced to use the model). Threshold for eradication R’ = R(1-v) where v = immune fraction. From [here](https://bmcmedicine.biomedcentral.com/articles/10.1186/1741-7015-7-30) we see that it’s mean R is 1.3 with a range of 0.9 to 2.1. Saving us playing with the math itself the first article says that if R = 2 then 50% of the population being immune would lead to eradication by herd immunity. [Seasonal influenza vaccine effectiveness (VE)](https://www.cdc.gov/flu/vaccines-work/effectiveness-studies.htm) overall ranges from a low of 19% (2014 to 15 season) to 60 in 2010 to 2011. Eyeballing it it looks like mid-40s is a reasonable expectation. (Reality is that it is different in different sub-populations, higher VE in kids for example than in the elderly.) So you can play with the math itself but roughing it out myself for the _average_ year I get R’=1.3(1-0.45) = 0.71 under the eradication threshold of 1. For a year that R is highest of the range though, 2.1, and lowest VE, 0.19, R’= 1.7, not under eradication threshold. Lastly [here’s](https://watermark.silverchair.com/ciu328.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAlYwggJSBgkqhkiG9w0BBwagggJDMIICPwIBADCCAjgGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMTWoTLE55QRsS-Z3JAgEQgIICCQYEVSABxfbGOi0xxK3JiPZNeQ_nQbNFo7HIbbYnFlHkwwpCXXxphHReUbgMbOB9XyxjtcOunEsf1Gi8IsL_l_gVVl6QDWX7ZGok1LRzf0ZI0-rt6QZJJd50nzA4i4emEk9wsP-Mwny4xND0gDRzn5_9epyQoLWaUvEtm3RJRgVdB1U3OBXzfRZEcowbY4-EMtud8waAGd8EfrvIz3XmHEZT13UcCjt7H5l87VMk1HgKqqOIiH704Fli_EamAaehLnqz6JXCWJcnVkJDjVT6uy5lOGT3ZcgIMFIWrHBRAi81Rv-7SzHP09uTi8KhsozQpXp4pCb4UCj-MK9TVzG6-vKSx4E_FFOWGINoU1nMTl1r6F0TQAJBLwQPkjEjkQsbMVEsqx5GrvwI-oJ4Osck6a6Ir_7C5vlpzJzeNXVeJvdAXlVbkYXX32BkA23Jgb4HusrtZiKDMAw1661pfQ-_VmMPxjJ0pjXkF3RauhJzn8wdq14_M2h98IvVtoR1-2v0IHyjGq-Kc-KBSdPXlifBDrs80mk3QrEjmRbbMnlm2Pi7uB5MhnCjrZSHzUnpWgFbWb2ypQMp-Ly9jyKJpP6kKdZQ2_fAbshAKF1drOWmONIYH-D2VnaFD2jmBIs7MRsKnKIW4jgQrR9dqO-a8lOEmkQ8dunhCWqy1WxqArs22acH-4-j-ElDLljN) some information just on what you are looking for looking only at the elderly population which has less VE and high morbidity/mortality under different scenarios. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [December 9, 2019, 1:54pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/3 "2019-12-09T13:54:02Z")
I’m assuming even if sub-eradication, you still get some sort of asymptotic decline in incidence rate? From which you can calculate “illnesses, sick days, hospitalizations, and deaths”. Also loss of GDP. ---
**Author:** ![Edward\_The\_Head](https://avatars.discourse-cdn.com/v4/letter/e/ce73a5/32.png) [@Edward\_The\_Head](https://boards.straightdope.com/u/Edward_The_Head)\ **Post date:** [December 9, 2019, 2:07pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/4 "2019-12-09T14:07:31Z")
I have a tag along question. The American flu shot is based upon what happens in Australia earlier in the year. So who does Australia base theirs on? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [December 9, 2019, 2:35pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/5 "2019-12-09T14:35:46Z")
> [@Edward\_The\_Head](#): > > I have a tag along question. The American flu shot is based upon what happens in Australia earlier in the year. So who does Australia base theirs on? Some very, very quick googling suggests that the flu bounces back and forth between the N and S hemisphere, basically following winter around. From that, I would assume that Australia’s is based on either ours or somewhere in Northern Europe. The flu seems to mutate as it travels, so it’s not that it’s an exact preventive, it’s their best guess for what will work. If Australia’s flu is responding to the H1N1 vaccine, we can use that. If that’s what they gave everyone and it’s not working, we’ll use something different. [Here’s](https://www.oregonlive.com/health/2019/11/this-years-us-flu-season-australias-results-mean-it-could-be-not-terrible-maybe.html) the article I very quickly skimmed. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [December 9, 2019, 3:49pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/6 "2019-12-09T15:49:04Z")
> [@Ruken](#): > > I’m assuming even if sub-eradication, you still get some sort of asymptotic decline in incidence rate? From which you can calculate “illnesses, sick days, hospitalizations, and deaths”. Also loss of GDP. For some value of “you” I am sure! At least for achieving eradication so [best case](https://www.sciencedirect.com/science/article/pii/S0264410X07003854)is here: > [@](#): > > Based on 2003 US population, we estimated that annual influenza epidemics resulted in an average of 610,660 life-years lost (undiscounted), 3.1 million hospitalized days, and 31.4 million outpatient visits. Direct medical costs averaged $10.4 billion (95% confidence interval [C.I.], $4.1, $22.2) annually. Projected lost earnings due to illness and loss of life amounted to $16.3 billion (C.I., $8.7, $31.0) annually. The total economic burden of annual influenza epidemics using projected statistical life values amounted to $87.1 billion (C.I., $47.2, $149.5). ---
**Author:** ![Edward\_The\_Head](https://avatars.discourse-cdn.com/v4/letter/e/ce73a5/32.png) [@Edward\_The\_Head](https://boards.straightdope.com/u/Edward_The_Head)\ **Post date:** [December 9, 2019, 3:55pm UTC](https://boards.straightdope.com/t/what-if-everyone-got-the-flu-vaccine/844589/7 "2019-12-09T15:55:54Z")
> [@Joey\_P](#): > > Some very, very quick googling suggests that the flu bounces back and forth between the N and S hemisphere, basically following winter around. From that, I would assume that Australia’s is based on either ours or somewhere in Northern Europe. > > The flu seems to mutate as it travels, so it’s not that it’s an exact preventive, it’s their best guess for what will work. If Australia’s flu is responding to the H1N1 vaccine, we can use that. If that’s what they gave everyone and it’s not working, we’ll use something different. > > [Here’s](https://www.oregonlive.com/health/2019/11/this-years-us-flu-season-australias-results-mean-it-could-be-not-terrible-maybe.html) the article I very quickly skimmed. Ok, that makes some sort of sense. At least enough for me to understand how it all works.