How can you tell if something is "worth it" without considering any costs (side effects, price, time, etc)?
You can use this number to estimate how fast a disease will spread, how likely it is to be successfully contained, or in the case of seasonal diseases, how many people will get it before seasonal societal changes (school getting out, people spending more time outside, etc.) will effectively curtail transmission for the year.
Looking at a vaccine on an individual basis, if it's only, say, 50% effective, that sounds pretty awful -- maybe almost not worth the bother. But on a society-wide basis, if every person were vaccinated, that would effectively knock the R0 value from 2 to 1, which is huge. Transmission is exponential: if you infect two people and they infect two people and they infect two people, etc., the total number of infected looks dramatically different than if everybody only infects one person. So in isolation it's only 50%, but societally, with high vaccination rates, there's a huge multiplicative effect that has the potential to dramatically reduce each person's risk of infection if vaccination rates are high enough. And that's still true even if it's even less effective than 50%, and has all sorts of economic and social consequences.
The R0 value refers to the potential for infection (ie in a 100% susceptible population it would be what you wrote).
>"But on a society-wide basis, if every person were vaccinated, that would effectively knock the R0 value from 2 to 1, which is huge. Transmission is exponential: if you infect two people and they infect two people and they infect two people, etc., the total number of infected looks dramatically different than if everybody only infects one person."
I just wrote a little SIR model and did not see this behavior. Depending on the parameters either 100% of the susceptible population was eventually infected, the infection died out quickly, or, if turnover was high enough (eg birth/death/viral mutation leading to a constant stream of susceptibles), there was a cycle and about the same number of people got infected either way.
Do you have a source for this behavior so I can see the details of the model?
The vaccine this year is about 32% effective against H3N2 in the US and 39% effective overall [0]. That's not amazing but it's definitely "worth it" for a few dollars and 5 minutes at a CVS.
[0]https://www.cdc.gov/flu/about/season/flu-season-2017-2018.ht...
What about side effects? https://www.cdc.gov/flu/protect/vaccine/general.htm
I'm not going to continue replying to this conversation because I can sense that it's going to become unproductive
If the virus is too infectious you need very high rates of immunization for it to work.
https://en.wikipedia.org/wiki/Basic_reproduction_number
Most of the time those R0 values assume "well mixed populations" (any one person is just as likely to contact any other person) amongst other things, so don't take them too seriously. However, the basic idea that you don't automatically get herd immunity is simple enough. Eg, just what I found quickly on the topic:
>"Whether vaccination of healthcare personnel can lead to a herd effect reducing laboratory-confirmed influenza among patients is still inconclusive. Pooled data from a Cochrane review of 3 cluster randomized controlled trials showed no reduction of laboratory-confirmed influenza (OR 0.86, 95% CI 0.44–1.68; p = 0.66), lower respiratory tract infections, admission to hospital (OR 0.89, 95% CI 0.75–1.06), and deaths from pneumonia (OR 0.82, 95% CI 0.45–1.49) in patients when healthcare personnel were vaccinated [35]. However, given that mathematical models suggest a herd effect [36], more rigorous studies need to be conducted." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171704/
https://www.hrsa.gov/advisorycommittees/childhoodvaccines/Me...
My point is that you can't say something "is worth it" without considering both costs AND benefits (I have recently seen friends get so ill they almost got fired because doctors ignored the side effects of prescriptions). Also, costs aren't zero just because they were prepaid or deferred.
Wrong calculation. The insurance company is trying to SAVE expenditures of doctors and hospitalizations; therefore, customers getting the flu shot cost the insurer less. Even further for herd immunity (the pt), 1 insured getting the flu shot might reduce 4-8 others from getting the flu.
Interesting point (not sure how far down a rabbit hole this can go...), so you are claiming that the introduction of flu shots has reduced insurance costs? Is it even possible to assess this or are there just too many confounds?
But it does objectively suggest that immunization is economically cheaper for insurers, with and without 100% immunization rates.
Obviously, there are many other factors in play as well but I don't think anything has been "objectively suggested" just because someone created a model that hasn't been (and probably will never be) tested.
Getting the flu, or having a more severe case of the flu increases your chances of 1) going to see a real doctor instead of a P.A 2) being mis-prescribed antibiotics 3) emergency room care 4) Torts originating from severe disease while in a Doctor's care
1 flu shot reduces probability of flu to ~70% of what it was before.
0.7 * Cost to treat average flu case + Cost Flu shot < 1.0 * Cost to treat average flu case
Insurance companies have pretty good stats underlying that sort of decision. At CMU this year, they were paying you to get a flu shot (in the form of a $5 gift card, with the flu shot being free).
Insurance, ultimately, is a way of sharing risk. Even more abstractly, it is about aligning interests. I think this is one part of why people get so upset with insurance when there is dispute - it feels a little like a betrayal.
I doubt current insurance companies care whether you get the flu or not. They just care whether you go to the doctor for it, eg if enough people think "It must be a cold" and self-medicate that works for them.