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Monday
Feb252013

What is the evidence that an "anti-vaccination movement" is "causing" epidemics of childhood diseases in US? ("HFC! CYPHIMU?" Episode No. 2)

note: go ahead & read this but if you do you have to read this.

This is the second episode of  “Hi, fellow citizen! Can you please help increase my understanding?”--orHFC! CYPHIMU?"--a spinoff of CCP’s wildly popular feature, “WSMD? JA!.” In "HFC! CYPHIMU?," readers competete against one another, or collectively against our common enemy entropy, to answer a question or set of related questions relating to a risk or policy-relevant fact that admits of scientific inquiry. The questions might be ones that simply occur to me or ones that any of the 9 billion regular subscribers to this blog are curious about. The best answer, as determined by “Lil Hal,”™ a friendly, artificially intelligent robot being groomed for participation in the Loebner Prize competition, will win a “Citizen of the Liberal Republic of Science/I ♥ Popper!” t-shirt!

I'm simply perplexed here. What's the evidence to support the claim that public resistance to childhood vaccination is connected to an  increased incidence of any childhood disease? Where do I find it?

If one does a Google search, one can easily find scores of alarming new sreports about "growing" anti-vaccine "movement" and its responsibility for outbreaks of diseases such as whooping cough.

But it's really really hard to find a news story that presents the sort of evidence that a curious and reasonable person might be interested in seeing in support of this genuinely scary assertion.

Look, I'm 100% positive that there are vocal, ill-informed opponents of childhood vaccination. Seth Mnookin paints a vivid, disturbing picture of them in his great book The Panic Virus. These groups assert that childhood vaccinations cause autism, a thoroughly discredited claim that has been shown to have originated in flawed (likely fraudulent) research.

If the question is whether we shoud condemn such folks, the answer is clearly yes.

But if the question is whether we should conclude that "[t]he anti-vaccine movement [has] cause[d] the worst epidemic of whooping cough in 70 years," etc., then we need more than the spectacle of such know-nothings to answer it. For such a claim to be warranted, there must be empirical evidence of (a) declining childhood vaccination rates that are (b) tied to disease epidemics.

Actually, it's pretty easy to find evidence-- outside of media reports on the anti-vaccine movement-- that tends to suggest (a) is false.  Consider this table from a recent (Sept. 2012) Center for Disease Control Morbidity and Mortality Weekly Report:


What it shows is DTaP vaccination rates for pertussis (whooping cough) holding steady at 95% for 3 or more doses and about 85% for 4 or more over the period from 2007-2011.

For MMR (mumps, measles, rubella), the rate hovers around 92% for the entire period. 

The rate of "children receiv[ing] no vaccinations" remains constant at about 0.7% (i.e., less than 1%). (In between these rows of data are rates for various other vaccinations -- like the one for Hepitatis B -- which all seem to show the same pattern. See for yourself.)

As for (b), it's also not too hard to find public health studies concluding that the outbreak in whooping cough was not caused by declining vaccination rates.  One, published recently in the New England Journal of Medicine, found that the incidence of whooping cough was actually slightly higher among children who had received a full schedule of five DTaP shots than those who hadn't, and that their immunity decreased every year after the fifth shot. That's not what you'd expect to see if the increased incidence of this illness was a consequence of nonvaccination.

"So what are the causes of today's high prevalence of pertussis?," asked a opinion commentary writer in NEJM.

 First, the timing of the initial resurgence of reported cases suggests that the main reason for it was actually increased awareness. What with the media attention on vaccine safety in the 1970s and 1980s, the studies of DTaP vaccine in the 1980s, and the efficacy trials of the 1990s comparing DTP vaccines with DTaP vaccines, literally hundreds of articles about pertussis were published. Although this information largely escaped physicians who care for adults, some pediatricians, public health officials, and the public became more aware of pertussis, and reporting therefore improved.

Moreover, during the past decade, polymerase-chain-reaction (PCR) assays have begun to be used for diagnosis, and a major contributor to the difference in the reported sizes of the 2005 and 2010 epidemics in California may well have been the more widespread use of PCR in 2010. Indeed, when serologic tests that require only a single serum sample and use methods with good specificity become more routinely available, we will see a substantial increase in the diagnosis of cases in adults.

In addition, of particular concern at present is the fact that DTaP vaccines [a newer vaccine introduced in the late 1990s] are less potent than DTP vaccines.4 Five studies done in the 1990s showed that DTP vaccines have greater efficacy than DTaP vaccines. Recent data from California also suggest waning of vaccine-induced immunity after the fifth dose of DTaP vaccine.5 Certainly the major epidemics in 2005, in 2010, and now in 2012 suggest that failure of the DTaP vaccine is a matter of serious concern.

Finally, we should consider the potential contribution of genetic changes in circulating strains of B. pertussis.4 It is clear that genetic changes have occurred over time in three B. pertussis antigens — pertussis toxin, pertactin, and fimbriae. . . .

Nothing about declining vaccination rates. Nothing.   

The writer concludes, very sensibly, that "better vaccines are something that industry, the Center for Biologics Evaluation and Research of the Food and Drug Administration, and pertussis experts should begin working on immediately."  

He also admonishes that "we should maintain some historical perspective on the renewed occurrences of epidemic pertussis and the fact that our current DTaP vaccines are not as good as the previous DTP vaccines: although some U.S. states have noted an incidence similar to that in the 1940s and 1950s, today's national incidence is about one twenty-third of what it was during an epidemic year in the 1930s."

I should point out too that in research I've done, I've just not found any evidence that a meaningful proportion of the general public views childhood vaccination as risky, or that there is any meaningful cultural divisions on this point.

Indeed, such vaccinations are one of the most commonly cited grounds members of the U.S. general public give for their (remarkably) high regard for scientists.

So ... what to make of this?  

Here are some questions:

1. Is there evidence I'm overlooking that suggests there really is a meaningful, measureable decline in vaccine rates in the U.S.? If so, please point it out, and I will certainly post it!

2. Is there evidence that nonvaccination (aside, say, from that in newly arrived immigrant groups) is genuinely responsible for any increase in any childhood disease? Ditto!

3. If not, why does the media keep making this claim? Why do so many people not ask to see some evidence?

4. If there isn't evidence for the sorts of reports I'm describing, is it constructive to make people believe that nonvaccination is playing a bigger role than it actually is in any outbreaks of childhood diseases? Might doing so actually reduce proper attention to the actual causes of such outbreaks, including ineffective vaccines?  Might they stir up anxiety by actually inducing people to believe that more people are worried about the vaccines than really are?

Can you please help increase my understanding, fellow citizens?


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Reader Comments (14)

It is not as apparent from the overall numbers, but the problem is the clustering of the unvaxxed. They cluster in places with Waldorf or Steiner schools, or certain locations where other "alternative" medical perspectives are the vogue.

Here's a piece on that: http://www.sciencebasedmedicine.org/index.php/pockets-of-vaccine-noncompliance-in-california/

In those places the rate drops below the herd level. If they become reservoirs for the wider community it's a problem. If you search for measles and Waldorf you'll see examples of them being the community source.

February 25, 2013 | Unregistered CommenterMary

@Mary:

Thanks!

I know there are enclaves like this; I think Seth Mnookin makes the case on that. And as I said, those enclaves are bad; they put themselves & others at risk.

But my question is whether that's what people have in mind when they talk about a "growing movement" that "causes" outbreaks etc?

If not, then what are they talking about?

If so, then why is that the right way to describe these enclaves? They don't seem to be a "growing movement" in any real sense; they are really very isolated. The link you sent emphasizes exactly that.


Finally, even in the story you sent me, there is no claim that the behavior of these particular defector/exempters has been linked to any increase in the incidence of any disease. Only an anxiety expressed -- which is reasonable -- that an increasing number of exempters in some communities creates risk. Fine to point that out.

But the news stories give the impression of an upsurge in public fear of vaccination as a result of the bogus autism study, a resulting decline in vaccination rates, and resulting disease outbreaks. So presumably they have something other than these very discrete communities in Calif -- or like ones in Washington state or Boulder Colo.-- in mind?

February 25, 2013 | Unregistered Commenterdmk38

I'll keep looking for the specific studies, I'm not really sure I grasp your distinction. Here's a study I remember in Europe:

"Ninety per cent of European cases were amongst adolescents and adults who had not been vaccinated or people where it was not known if they had been vaccinated or not."

http://www.bbc.co.uk/news/health-15999492

I personally attended a CDC meeting in my city where they were discussing H1N1 vaccination. Of about 100 people in the room, at least 80% were rabid anti-vaxxers. I don't live in a particularly alt-medish place (Boston). We like our science and tech here for the most part.

February 25, 2013 | Unregistered CommenterMary

Here's some of the other types of things that I see that lead me to think that non-vaccination is driving outbreaks. Some of it is news, some of it is publications. And unvaxxed or incomplete vax spread has consequences for waning immunity situations as well. If they weren't the main reservoirs, declining efficacy wouldn't be as much of an issue.

http://www.bbc.co.uk/news/uk-england-cornwall-14505415
This is the highest level for 13 years, but still falls short of the 95% required to stop the spread of the disease in the community.

http://www.bbc.co.uk/news/education-15002750
The organisation said these cases have been associated with small clusters in universities and schools, with many of the patients unvaccinated.

http://news.bbc.co.uk/2/hi/uk_news/england/sussex/8074211.stm
He said it was "pretty clear" that the surge in cases followed a "far too low" uptake of MMR vaccinations.

http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20395
Between January and August 2011, the canton of Geneva, Switzerland, experienced a large measles outbreak with 219 cases (47 cases per 100,000 inhabitants) in the context of an extensive epidemic in a neighbouring region of France. Most cases were young adults (median age: 18 years), often unaware of their vaccination status. The vast majority of cases were either not (81%) or incompletely vaccinated (8%). ...Data collected locally indicated that the main reason for not vaccinating children were concern for side effects and the belief that natural infection contributed more to better health than vaccination [16].

And this has consequences--Swiss measles are what got San Diego in the past:
http://www.ncbi.nlm.nih.gov/pubmed/20308208
"an intentionally unvaccinated 7-year-old boy who was unknowingly infected with measles returned from Switzerland, resulting in the largest outbreak in San Diego, California, since 1991....Although 75% of the cases were of persons who were intentionally unvaccinated..."

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6133a2.htm
Among the U.S. measles cases in persons aged 16 months through 19 years reported in 2011, 76% were in persons not vaccinated for a nonmedical reason (1).

February 25, 2013 | Unregistered CommenterMary

No fair, off-line commentators!

The best I could find was the CDC reporting in 2008 about an "upward trend" in the "mean proportion of school children not being vaccinated because of personal belief exemptions" from 1991 to 2004. (see below) But the *tone* in the pieces I quote below seem quite grim . . . the data does not seem quite as grim as the tone.

Measles --- United States, January 1--April 25, 2008
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5718a5.htm

"An upward trend in the mean proportion of school children who were not vaccinated because of personal belief exemptions was observed from 1991 to 2004 (7)."

(7) Omer SB, Pan WK, Halsey NA, et al. Nonmedical exemptions to school immunization requirements: secular trends and association of state policies with pertussis incidence. JAMA 2006;296:1757--63.


http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5718a5.htm
Measles --- United States, January 1--April 25, 2008

"Many of the measles cases in children in 2008 have occurred among children whose parents claimed exemption from vaccination because of religious or personal beliefs and in infants too young to be vaccinated. Forty-eight states currently allow religious exemptions to school vaccination requirements, and 21 states allow exemptions based on personal beliefs.*** During 2002 and 2003, nonmedical exemption rates were higher in states that easily granted exemptions than states with medium or difficult exemption processes (7); in such states, the process of claiming a nonmedical exemption might require less effort than fulfilling vaccination requirements (8).

"Although national vaccination levels are high,††† unvaccinated children tend to be clustered geographically or socially, increasing their risk for outbreaks (6,9). An upward trend in the mean proportion of school children who were not vaccinated because of personal belief exemptions was observed from 1991 to 2004 (7). Increases in the proportion of persons declining vaccination for themselves or their children might lead to large-scale outbreaks in the United States, such as those that have occurred in other countries (e.g., United Kingdom and Netherlands) (10).

"Ongoing measles virus transmission has been eliminated in the United States, but the risk for imported disease and outbreaks remains. High vaccination coverage in the United States has limited the spread of imported measles in 2008. Nevertheless, the measles outbreaks in 2008 illustrate the risk created by importation of disease into clusters of persons with low vaccination rates, both for the unvaccinated and those who come into contact with them."

(6) Parker AA, Staggs W, Dayan GH, et al. Implications of a 2005 measles outbreak in Indiana for sustained elimination of measles in the United States. N Engl J Med 2006;355:447--55.

(7) Omer SB, Pan WK, Halsey NA, et al. Nonmedical exemptions to school immunization requirements: secular trends and association of state policies with pertussis incidence. JAMA 2006;296:1757--63.

(8) Rota JS, Salmon DA, Rodewald LE, Chen RT, Hibbs BF, Gangarosa EJ. Processes for obtaining nonmedical exemptions to state immunization laws. Am J Public Health 2001;91:645--8.

(9) Smith PJ, Chu SY, Barker LE. Children who have received no vaccines: who are they and where do they live? Pediatrics 2004;114:187--95.


http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6004a1.htm
County-Level Trends in Vaccination Coverage Among Children Aged 19--35 Months --- United States, 1995--2008
Surveillance Summaries
April 29, 2011 / 60(SS04);1-86

Philip J. Smith, PhD
James A. Singleton, MS
National Center for Immunization and Respiratory Diseases

"Clusters of children who did not receive any vaccine doses were found in specific geographic areas, with the largest numbers of unvaccinated children living in counties in California, Illinois, New York, Washington, Pennsylvania, Texas, Oklahoma, Colorado, Utah, and Michigan (3). In Ashland, Oregon, 12.3% of all children attending public schools and 18.8% of children attending day-care facilities in 2002 claimed an exemption from mandatory vaccination laws, compared with 2.4% for the entire state (4,5).

"Children of parents who refuse vaccine doses have an increased risk for acquiring and transmitting measles and pertussis (6), and in small geographic areas with a preponderance of children whose parents have refused vaccine doses, an increased risk for pertussis and measles exists among members in the community (6--8). In 2008, the index cases for three of four measles outbreaks outbreaks in small geographic areas were in children whose parents had refused vaccine doses (9,10)."

(6) Omer SB, Salmon DA, Orenstein WA, et al. Vaccine refusal, mandatory immunization, and the risks of vaccine-preventable diseases. N Engl J Med 2009;360:1981--1988.

(7) Omer SB, Enger KS, Moulton LH, et al. Geographic clustering of nonmedical exemptions to school immunization requirements and associations with geographic clustering of pertussis. Am J Epidemiol 2008;168:1389--96.

(8) Salmon DA, Haber M, Gangarosa EJ, et al. Health consequences of religious and philosophical exemptions from immunizations laws: individual and society risk for measles. JAMA 1999;282:47--53.

(9) CDC. Measles---United States, January 1--April 25, 2008. MMWR 2008;57:494--8.

(10) CDC. Update: measles---United States, January--July 2008. MMWR 2008;57:893--6.

February 25, 2013 | Unregistered CommenterIsabel Penraeth

@Isabel & @Mary: Thanks!

You two are now battling it out for the coveted "I [heart] Popper" jersey; the issue of whether off-line responders can participate appears to be moot.

@ Mary: Again, I think the fact that nonvaccinated are more likely to contract a disease is not disputed. Also not in itself a basis for the sorts of claims I'm asking about unless we think that the number of nonvaccinated & incidence of diseases are increasing. And in US. It is the claim that we are observing some general trend toward nonvaccination & resulting increases in disease in US that is being widely asserted; it is that proposition for which I'm interested in seeing evidence.

There doesn't seem to be such evidence in connection with whooping cough, which (as reflected in my post) has been the main focus of late.

Here is something from a 2012 CDC Report that's relevant to the claim that growing nonvaccination in US might be linked to increase in measles in 2011:

In 2000, the United States achieved measles elimination (defined as interruption of year-round endemic measles transmission) (1). However, importations of measles into the United States continue to occur, posing risks for measles outbreaks and sustained measles transmission. During 2011, a total of 222 measles cases (incidence rate: 0.7 per 1 million population) and 17 measles outbreaks (defined as three or more cases linked in time or place) were reported to CDC, compared with a median of 60 (range: 37–140) cases and four (range: 2–10) outbreaks reported annually during 2001–2010.

The same CDC Report indicates, however, that 90% of the cases originated in "importation" from countries outside the U.S. "The increase in importations," the report states, "reflects recent increases in the incidence of measles in countries visited by U.S. travelers." The "source of almost half of the measles importations in 2011 was the WHO European Region .... Five countries (France, Italy, Romania, Spain, and Germany) accounted for more than 90% of cases reported to the European Centers for Disease Prevention and Control." The UK, as Mary's links suggest, also apparently has seen "reestablishment of endemic transmission."

Sensibly, then, the CDC instructs "providers should remind their patients who plan to travel internationally of the increased risk for measles and potential exposures during bus, train, or air travel and at large international events or gatherings (e.g., Euro 2012 and the 2012 Summer Olympics), and of the importance of vaccination."

"Maintenance of high MMR vaccination coverage is essential to prevent measles outbreaks and sustain measles elimination in the United States," the Report states. "Despite the relatively small number of reported cases in the United States, the public and the health-care providers must remain vigilant."

Good advice, certainly.

But my question is whether it's accurate -- and a good way to convey information about risk -- to turn this report into this: "Measles Invades The U.S. As The Anti-Vaccine Movement Scores Again"? Or this: "measles appears to be making a comeback" because "unfounded fears of vaccines have prompted a growing number of parents to not have their children immunized"?

February 25, 2013 | Registered CommenterDan Kahan

I don't understand why you think importation is a relevant distinction. The same dynamic exists in those places where this comes from. It's very prevalent in Switzerland, I had a scientist friend who accidentally rented an apartment and found he lived in an Anthroposophy community, and it made him nuts. And that's the source for an unvaxxed American very possibly.

It's brutal in Australia too. Their anti-vax movement is quite serious. Same thing in France--a different original trigger, but a source of rampant European problems.

Importation doesn't mean from someplace where this wasn't under control before. It's the same exact problem.

February 26, 2013 | Unregistered CommenterMary

I don't understand why you think importation is a relevant distinction

hmmm. It does seem like the question of importation doesn't comprehensively address the larger question.

If a significant increase in prevalence of non-vaccination in the US can't be established, increased disease prevalence in the US could be linked to the anti-vaccine movement by virtue of more Americans traveling to other countries where there is an established increase in prevalence of non-vaccination.

February 26, 2013 | Unregistered CommenterJoshua

I'll let other, better minds speak to your epidemiological concerns, but I need to chime in here to assure you that the word "movement" absolutely captures the nature of vaccine-resistance in this country. I don't know if you're a parent, but among parents, vaccine-hesitancy is widespread, even among parents who ultimately choose to vaccinate. The anti-vaccine movement was responsible for derailing commonsense immunization law improvements in Vermont last year, for example, because they successfully organized a letter/e-mail-writing campaign to those legislators considering a bill that would remove philosophical exemptions from immunization law. They are currently pressuring Oregon legislators not to adopt better immunization law, and they are back in Vermont, demanding legislators vote against another immunization rule. They are single-handedly responsible for the MMR-autism claim, which many people believe lead to vaccine-resistance, in its current form, all over the world, and they are the reason you even mention the vaccine-autism connection, something that was thoroughly discredited, withdrawn, and accused of being fraudulent. Chiropractors are, almost to a man, anti-vaccine, and considering how well integrated they are into mainstream medicine, this, too, qualifies as part of a movement. These kinds of things are hard to see in epidemiological data, but are easy to see in day-to-day life. Just ask any health care provider if he or she is spending a great deal more time assuring parents about vaccines than they did before Jenny McCarthy started spouting off about vaccines and autism. Or ask any new parent what her "research" online about vaccines has yielded.

February 26, 2013 | Unregistered CommenterAshley Shelby

It's really the principle of the matter. Why would you want to validate these morons in any way? Peoples lives are at stake.

February 26, 2013 | Unregistered CommenterHardy

@Ashley: Thanks. I think that helps me to understand better an important political component of the issue -- & appreciate the very appropriate resentment & anger toward the "movement" understood as a determined & cohesive community of dangerous people.

I've reflected a bit in responise to some responses & more readings & have tried to make the motivations for my questions clearer, in way that would now move me to reframe question a bit.

My anxienty is not that anyone is exaggerating the mischief of the "movement" in sense of an organized faction of cranks trying to interfere with public health. Or that anyone is exaggerating the appropriateness of resisting them if they do things in Vermont or other states.

What I'm anxious about is the implication that there is growing "movement" in form of general public opinion against vaccines in the US. Real growing concern, resulting in measureable dips in immunization levels that are compromising herd immunity and creating epidemics. If that's true, then we should be told that, certainly.

But if it isn'tn, then saying that's so can actually be counterproductive. People treat other people's fears as evidence that there is reason to be fearful. If, then, people begin to sigbnificantly overestimate the number of people who are opting out, that would likely be a bad thing.

One reason I believe I worry that such an impression is being created by news reports & some advoacy groups is that people ask me all the time "what explains the growing public concern with vaccines?" If I say, "why do you believe there is growing *public* concern?," they say "becuase of the epidemic of whooping cough &other childhood diseases."

They are minsinformed. They are surprised to learn that vaccination rates aren't dropping for whooping cough, MMR, hep B. Whooping cough, which is now exhibit A, reflects an ineffective vaccine, not nonvaccination.

I don't accept that it "validates morons" to recognize that the US public is overwhelmingly pro-vaccine & overwhelmingly vaccine compliant. I think it helps people to see that those who are resisting vaccines are true social outliers!

Of course, if I'm misinformed on the facts -- I'm asking for evicence here to see what I can figure out-- I want to know.

Also, if I'm not misinformed on the facts, but the sorts of reports I'm pointing to reflect a deliberate decision to use such language anyway, I'd like those who are doing it to say so. We can then have a discussion about whether that's a sensible risk communication strategy.

As @Hardy correctly points out, people's lives are at stake. So we should use the science of science communication to make sure the medical science involved in vaccines has the appropriate effect it should in our nation's public health policies.

Both of you -- @Ashley & @Hardy -- please tell me if this seems like a sensible set of concerns. I'm pretty sure I attach the same value you do to universal vaccination: vaccines are one of the great benefits that science has conferred on liberal society in reciprocation for liberal society being historically suited to scientific inquiry. My guess is that we will converge if we discuss this -- or at least both end up w/ views in which we have reason to be more confident

February 26, 2013 | Registered CommenterDan Kahan

My understanding of how the production of flu vaccine works is that, in the absence of an outbreak which provides an actual real-time flu virus to model and match the vaccine on, an educated guess is made as to which specific flu virus will predominate and then the vaccine is made based on that guess. If in reality the flu virus is different, than that particular vaccine would be worthless in preventing the virus from spreading.

If this is accurate, than other behavior which would enhance the bodies capacity to resist viruses - optimizing nutrition, emotional and mental health, adequate sleep, for example - may be just as, or more effective in combating the flu virus.

I don't know how mumps, measles and chickenpox viruses and bacteria arise; I will here assume that they don't mutate in the same manner as the flu virus. Which means that the vaccines produced to combat them are an actual match for these viruses and bacteria.

Accordingly, the efficacy of mumps, measles and chickenpox vaccines is probably very high, based as they are on the structure and dynamics of relatively known and unchanging pathogens; while the efficacy of the flu vaccine is probably lower, based as it is on a supposition as to which strain will become prevalent.

In this scenario, it seems reasonable to accept vaccination for so-called childhood diseases, and not unreasonable to decline the flu vaccine.

March 3, 2013 | Unregistered CommenterRobin Donald

@Robin:

Good points.

I agree: no question it's very unreasonable to decline vaccine for childhood diseseases.

But it's a separate question whether fluctuations in incidence of childhood diseases are attributable to reduced vaccination rate. That claim cointinues to be made about whooping cough, even though public health study has concluded that the source of the epidemic was not reduced vaccination but rather combintion of weak booster shot & change in strains of virus.

If the claim is that it "can't hurt" to over-attribute bad consequences to bad behavior, that's another story. I don't think it's a good idea, especially if it conveys a false impression about the prevalence of nonvaccination -- a point I take up in this post & in this one.. I prefer Ahsley Shelby's message: We are the 95% who vaccinate & we are mad at the 5% who don't. It's factual; it doesn't risk exaggerating fear by exaggerating the general level of defection; and it reinforces commitment to protecting a public good.

Also, I think a reasonable argument can be made that it is irresponsible not to get the flu vaccine too. The estimated annual death toll is typically put at over 30,000 -- about the same number that die from automobiles. Most people who get the flu don't die, of course. But they are still implicated in transmitting it to others, including those in vulnerable populations (typically very young & very elderly) for whom death rate is higher. There are also *huge* economic costs due to people missing work. The vaccine might not be as effective in a given year as hoped-- but that just goes to the probability that the failure to get vaccinated will contribute to a higher than necessary incidence of the disease.

March 3, 2013 | Unregistered Commenterdmk38

Declining efficacy is a possible cause, but it also may be that the efficacy of the vaccine in the first place was insufficient in a highly infected population. That is, even without a decline in vaccine efficacy, an increase in exposure may be all that's needed to make vaccine ineffective. That could be taking place in enclaves of anti-vaxxers and may be exacerbated if vaccine efficacy is, in fact, declining.

April 6, 2014 | Unregistered CommenterSteven Damron

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