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Last week I stumbled upon an article which stated that vaccination from polio is totally unnecessary for infants in first world countries. The article cited a bunch of questionable sources like mercola.com, but also had some references to information provided by WHO.

I decided to check what WHO says about it. WHO page about polio has a link to Data and statistics, which states, that in past couple of years there have been very few cases of polio (100-200 cases a year - all of them in Afghanistan, Nigeria and Pakistan).

So I wonder: are claims, that vaccination from polio is not necessary, reasonable? It looks like they are fighting a disease that's almost non existent (as opposed to influenza for example, of which there are 3 to 5 million cases of serious illness each year).

valentinas
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    this claim no doubt falls into the same category as claims that vaccination causes autism. – jwenting Apr 10 '13 at 05:59
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    The REASON it's not common, IS because of the vaccination. I read an article about it somewhere, I can maybe dig it up. But it said that in the US lots of anti-science religious people are against vaccinations, and that in some communities they have huge outbreaks of polio then, and a bunch of kids dies. As long as the numbers stay low of non-vaccinated, they are protected by the others vaccinations, because majority of community is immune, and thus no one gets it. If too many stay unvaccinated, the community is vulnerable, and then there can be a big outbreak. – Wertilq Apr 10 '13 at 07:07
  • There's a big difference between _infants_ and _at all_. Which one are you asking about? – Rex Kerr Apr 10 '13 at 19:34
  • @RexKerr good point. I think I'm more interested about vaccination from polio in general, not specific to infants. – valentinas Apr 10 '13 at 21:25
  • @Wertilq any chance you could mention a source? – valentinas Apr 10 '13 at 21:28
  • @valentinas - hunter2's answer is what you want, then, I think. The answer for infants is more complex, but basically goes: if you herd your infants, you'd better immunize them (or one sick infant will get everyone else sick). Otherwise, they can take advantage of herd immunity in the rest of the population (they'll never catch it because the people they're exposed to are immune). There are various theoretical results regarding infection models that make these ideas more precise. (There is another reason to do it early: babies are seen often by pediatricians, so it's more likely to happen.) – Rex Kerr Apr 10 '13 at 21:32
  • "Is vaccination from polio necessary in first world countries?" Necessary? Well, it's cheap insurance. Being one of the fraction of people who got polio and lived to tell about it, I'm one datapoint who says "Why risk it?" – Mike Dunlavey Apr 10 '13 at 21:44
  • @valentinas what you see in hunter2's answer is the source I dug up. – Wertilq Apr 11 '13 at 04:44

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Yes due to community immunity.

Unimmunized persons are protected—indirectly—against some infectious diseases by being surrounded by immunized persons. This is known as community (or “herd”) immunity.1

There is a 'community immunity' where the more people have the vaccine, the harder it is for the disease to spread. Conversely, vaccines have a rate of effectiveness - they don't work perfectly 100% of the time; between that and people with compromised immune systems, even if most people get the vaccine, there is always a small segment of the community that is vulnerable. So, people who choose not to get the vaccine put themselves and the whole community at risk.

Reason why it's important with community immunity, is that no vaccine is 100% working, so on top of the vaccine preventing the disease, the community need to be as clean as possible from it.

Reaching the thresholds for these diseases is important for the public health because no vaccine is 100% effective. 1

One small note though, as far as I know the 'anti-vax' movement is not particularly a religious thing, although they are clearly unscientific. They are also not limited to the US (there are similar groups in the UK, for example).

There are also, separately, religious groups (i.e. Christian Scientists) who object to most/all medicine on religious grounds, without denying any of the science involved.

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hunter2
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    the anti-vaccination crowd are mostly religious, though there's a smaller subset who object because it's a government mandate and they either don't trust the government or consider the sanctity of their bodies to be something the government has no authority to determine (usually both, often combined with religious reasons as well). – jwenting Apr 10 '13 at 10:13
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    I wouldn't agree with such a generalization. For example opposing swine flu vaccines has quite firm scientific grounds, in 1976, swine flu killed 1 person, while the vaccine killed 25. – vartec Apr 10 '13 at 10:30
  • Thank you for referring to me and what I mentioned in the comment, but it's a cleaner answer if you don't refer to me, and instead refer to a proper source. So while your answer is good, and correct, you need to add references to what you claim, like in proper science. I only edited first part, you are free to add a reference to which groups it is that is against vaccination. Even if it's not completely on-topic, it's still an interesting piece of data IMO. – Wertilq Apr 10 '13 at 10:55
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    @jwenting I'd argue against the point of the anti-vaccination crowd being mostly religious as well. That's not to say that there aren't some who object to vaccinations on religious grounds but most of the movement that has been in the recent news has been objection on "scientific" grounds in the belief that vaccinations lead to autism. – rjzii Apr 10 '13 at 11:48
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    @RobZ: exactly, there been some "vaccines contain mercury which causes autism" conspiracy theory. IIRC it has been addressed in a question here. – vartec Apr 10 '13 at 12:00
  • @Wertilq, Yes, thank you, your points are well taken. I did suspect that standards for proof/citations would be higher here than on other SE sites, but I was/am lazy - one reason I would have posted as another comment if I could have. (At the same time, your comment would have made a good answer, especially with the link you edited into mine.) Anyway, good collaborative answer. Re: the anti-vax thing, Rob and vartec are saying what I was thinking of ... I'll see if I can find a link. – hunter2 Apr 10 '13 at 12:45
  • Also, I had previously used the term "network effect" where this answer now uses "community immunity". The latter may be more specific/accurate, but I have heard the former used in discussing this topic; for what it's worth, "network effect" is a similar concept. – hunter2 Apr 10 '13 at 12:48
  • Yea the reference I added called it "community immunity" so I edited that for consistency, having same term throughout the answer. – Wertilq Apr 10 '13 at 12:57
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    Yup, just added that comment to keep both terms on the page, to be (unnecessarily) thorough. Found and added a couple links. As @vartec said, it has been addressed here. Might not be the best link to provide, but they have links to real sources (and further discussion) over there. – hunter2 Apr 10 '13 at 13:01
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    @jwenting Your evidence for the anti-vax movement being religious? – DJClayworth Apr 10 '13 at 13:01
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    The question is at leat motivated by not whether _people_ need to be immunized but _infants_. Your answer does not at all address whether it'd be okay to skip immunizing infants and immunize e.g. before entering preschool (i.e. past infancy). – Rex Kerr Apr 10 '13 at 19:33
  • Just to clarify: whether the claimants are religious or not does not affect the validity of claim. The claim could still be valid, maybe for different reasons, but again, it doesn't matter. I'm just interested if it's valid or not. Thanks for the bit about network effect (or in case of vaccination the lack of it) and the community immunity, that makes a lot of sense. – valentinas Apr 10 '13 at 21:31
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    A reasonable summary article on herd immunity is http://cid.oxfordjournals.org/content/52/7/911.full with figure 2 being of particular note (showing on the left the relationship between infectiousness and what fraction of the population needs to be immunized to achieve herd immunity, and on the right how the number of cases varies as you approach that limit for one example of infectiousness). – Rex Kerr Apr 10 '13 at 21:36
  • @RexKerr, yes, that's a valid dichotomy, and a finer-grained question (than what Wertilq and I addressed). I guess the question then would be "What risks do the vaccine present to infants, and do they outweigh the benefits of early/infantile vaccination?" Fair point, although going on the title, and Val's response to a comment of yours I think we've covered the original question. (But yes, I do see that the question itself refers to infants). Thanks for the link, edit in in if you want. Yes Val, of course agreed re religion/validity, was responding to a (related if tangential) comment. – hunter2 Apr 11 '13 at 13:25