The Disneyland measles outbreak has the anti-vaccine movement on the ropes a bit. As I and pretty much all of my colleagues at Science-Based Medicine have predicted for years, once previously contained infectious illnesses start to seriously return, public opinion will shift against the anti-vaxxers.

We are seeing more mainstream stories like this one, Mom: Family that refused vaccination put my baby in quarantine, from CNN, and this one, Vaccine deniers stick together. And now they’re ruining things for everyone, from the Washington Post. As I mentioned in my earlier post, The Onion also nailed it with this satire, I Don’t Vaccinate My Child Because It’s My Right To Decide What Eliminated Diseases Come Roaring Back.

Of course, the cranks are unmoved. Their position is not based on a rational assessment of the evidence, and therefore evidence will not move them from their perch. What they have been doing is repeating tired anti-vaccine tropes. Unfortunately they are getting some exposure from residual false balance in the media.

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This is an ongoing story that isn’t over yet. As it has been raging for days now, most people have probably heard that there is a big measles outbreak starting in Disneyland in California. There are now 87 confirmed cases of measles, 50 of which can be directly linked to Disneyland. Of the 42 people so far whose vaccination status is known, 34 were unvaccinated, 3 were partially vaccinated, and 5 were fully vaccinated.

Yes, this is caused by those who are not vaccinated

One thing is absolutely certain from these numbers – this outbreak has largely been caused by those who are not vaccinated. As you can see, most of those affected are unvaccinated. The vaccination rate for MMR is about 90% in the US. This means those who are unvaccinated were about 67 times more likely to be infected with measles in this outbreak than those fully vaccinated.

If vaccination rates were higher, then herd immunity could have stopped or severely limited the spread of the disease. That is the point of herd immunity – if enough people are protected then the virus is less likely to find a vulnerable host and continue the spread. The vaccine is about 97% effective in those fully vaccinated, which is why there were a few vaccinated people who contracted the disease.

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A new systematic review of adverse events from vaccines used in the US was recently published in the journal Pediatrics: Safety of Vaccines Used for Routine Immunization of US Children: A Systematic Review. (Full text pdf) This systematic review is actually an update and expansion to the 2011 Institute of Medicine (IOM) report on vaccine side effects.

The review looked at the best evidence available, active surveillance studies with controls, identifying 67 relevant studies. Overall they found that vaccines were very safe. There were a few associations with serious adverse events, but these were all very rare. From their conclusions:

Our findings may allay some patient, caregiver, and health care provider concerns. Strength of evidence is high that MMR vaccine is not associated with the onset of autism in children; this conclusion supports findings of all previous reviews on the topic. There is also high-strength evidence that MMR, DTaP, Td, Hib, and hepatitis B vaccines are not associated with childhood leukemia.

Evidence was found for an association of several serious AEs with vaccines; however, these events were extremely rare: absolute risk is low. For example, strength of evidence is moderate for association of vaccines against rotavirus with intussusception. Although 1 large US epidemiologic study found no association, a recent analysis of the US PRISM program found both RotaTeq and Rotarix associated with intussusception in the short term. Estimated rates were 1.1 to 1.5 cases per 100 000 doses of RotaTeq and 5.1 cases per 100 000 doses of Rotarix.

So a few vaccines are associated with rare AEs. Given the rhetoric of the anti-vaccine movement, there are a few points worth emphasizing here.

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There are some topics I just have to revisit from time to time. I consider this a public service announcement. So far this year there have been 288 confirmed cases of measles. This is the largest number of cases since endemic measles was declared eliminated from the US. The previous worse year was 2011, which saw 220 cases total. 

There is no question that this is tied to vaccine non-compliance. The anti-vaccine movement is scaring people with misinformation and pseudoscience into not vaccinating their children, and as a result we are seeing the return of vaccine-preventable diseases.

When a disease is endemic that means there is a self-sustaining infection – there is always someone infected somewhere and it keeps getting passed around. The MMR vaccine (especially after the second dose was added) resulted in herd immunity, which is a high enough immunity rate so that the infectious disease cannot be passed around indefinitely. High vaccination rates in the US resulted in eliminated measles as an endemic disease by 2000.

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One common feature of unscientific belief systems is that they do not change in the face of new evidence. They tend to evolve like cultural beliefs or marketing campaigns, but do not appear to be affected by scientific evidence in any meaningful way.

One great example of this is the idea the autism is linked to vaccines (to be clear up front, it isn’t) This idea had a few important factors in its origin. The first was simply the existing anti-vaccine movement searching for anything to blame on vaccines. The second, and perhaps decisive, factor was the now discredited and withdrawn study by Andrew Wakefield linking autism to the MMR vaccine.

Even as the MMR claim was dying, the anti-vaccine community was moving onto the next target – mercury (specifically the preservative Thimerosal). This was the target of the book Evidence of Harm by David Kirby. This also created common cause between the anti-vaccine movement, and separate “mercury militia” blaming many modern ills on mercury, and some environmentalists (most prominently Robert Kennedy Jr.) who are keen to blame medical problems on any environmental exposure, including mercury and/or vaccines.

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Facebook is like a graveyard in a zombie movie, where old news items rise from the dead to have a second life. I am often asked about news items that are burning up Facebook, only to find that they are years old, but never-the-less they have to be addressed all over again. ]

One such item (actually a few items) is a 2012 news report about the Italian courts awarding money to the Bocca family a large reward because it concluded their 9-year-old son acquired autism from the MMR vaccine.

History here is a useful guide. The courts have historically often been out-of-step with the science, tending to err on the side of awarding compensation for possible harm. For example, until about the 1920s it was thought that physical trauma could cause cancer. Animal studies and epidemiological evidence, however, showed that there was no causal connection. Recall bias and increased surveillance were likely the cause of the apparent association.

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A new study, not published but to be presented at a meeting, purports to show that after the infamous Andrew Wakefield 1998 Lancet article alleging a connection between the MMR vaccine and autism, vaccination rates in the US declined by about two percent. This may seem like a small amount but has an effect on public health, and vaccine refusal typically occurs in pockets that bring vaccination rates below the level needed for “herd” immunity, allowing for outbreaks.

This, however, is all old news. There are two other pieces of information in the study that are interesting. The first is that the decrease in vaccination rates did not rebound after Wakefield and his Lancet study were thoroughly refuted. That genie was out of the bottle, and correcting the misinformation did not have the desired effect of putting it back in. This too is in line with other research and experience. It is easier to spread fear than reassurance. Once rumors are spread the damage cannot be undone.

The study also purports to find that the there was an inverse relationship between education level and vaccine use – college-educated mothers were less likely to vaccinate their children. Further, in the 8 years after the Lancet study this gap increased. This education-gap is also in line with previous research, but needs some explanation. We need to distinguish unvaccinated from undervaccinated, and vaccine non-compliance from vaccine refusal. When looking at the undervaccinated, and specifically those who missed scheduled vaccines, this correlates with lower socioeconomic status and less education. This is in line with a more general pattern – the fewer resources a family has the less likely they are to avail themselves of available health care.

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Yet another study showing that clear signs of autism are present as early as six months of age has been published. In this study researchers looked a high-risk children (siblings of children with autism) at 6 months with MRI scanning (specifically diffusion tensor imaging) and then evaluated them clinically at 24 months to see which children met criteria for autism spectrum disorder (ASD). Some of the children also had imaging at 12 months. The imaging was used to look at the development of white matter – the tracks in the brain that contain the axons or pathways of communication.

When compared as groups the 28 infants who went on to develop ASD had significantly decreased white matter development in 12 of 15 brain pathways examined in comparison to the 64 infants who did not develop clinical ASD.  These results are very robust, although I should point out that the children were compared as groups, not individuals. The purpose of this study was to see if there were detectable changes in the brains of children with ASD at 6 months, not necessarily to explore its utility as a diagnostic tool that can be applied to an individual.

Still, this study supports other research providing increasing evidence that ASD begins at least as early as 6 months. It is probable that ASD begins earlier than 6 months, actually, because in order for detectable differences to be present in the brain, development must have been heading down a different trajectory prior to that. These kinds of studies have not looked at children younger than 6 months, and it would be interesting to see how early such changes can be detected. But even without that data, we can conclude the whatever process results in ASD it is active prior to 6 months so that the effects are detectable at 6 months.

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Perhaps the weak link in the effectiveness of vaccines is public acceptance. Individual vaccine types vary in terms of their effectiveness, but all are reasonably effective and very safe. Vaccines are, in my opinion, one of the “home runs” of modern medicine – scientists hit upon a way to marshal our own immune systems to make us resistant or even completely immune to certain infectious diseases. The result has been a dramatic decrease in diseases that used to plague humanity, and the complete eradication of one (smallpox).

It is ironic that the greatest barrier to the effectiveness of the vaccine program is public acceptance. Part of the problem is that very high acceptance is needed in order to achieve what is called “herd immunity” – where there is sufficient protection in the population that an infected individual will likely not cause an outbreak.

In the US the numbers are pretty good, and have remained so even through the recent increase in the anti-vaccine movement. About 68% of children complete the full routine vaccination series. Many of the individual vaccines have compliance rates in the 90s (MMR, for example, was 92.1% in 2008). The level required for herd immunity varies, but it is generally around 85-90%.

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The news that Power Balance has filed for bankruptcy is both encouraging and disheartening at the same time. I’ll explain – but first for background: Power Balance is the company who made millions of dollars selling little plastic wrist bands embedded with a cheap hologram. It love it when people become millionaires selling pet rocks or hoola hoops. Come up with a unique idea that catches on and you deserve to rake it in. Power Balance, however, made their millions selling dubious claims.

They claimed that their little pieces of plastic could improve balance, energy, and athletic performance. Their marketing was very effective, with celebrity sports star endorsements and live demonstrations in malls. Their demonstrations were indistinguishable from old parlor tricks that have been recycled numerous times to sell many dubious products.  The SkepticBros even started selling (at their cost of about $1) Placebo Bands, which they believe are just as effective (i.e. nothing but the placebo effect) as Power Balance or any similar product.

The skeptical community has seen this all before. We targeted the claims of Power Balance, exposing the fact that they are highly implausible, the claims themselves are incomprehensible techno-babble, and there is no credible scientific to back them up. The Australian Skeptics lead the charge, resulting in the ACCC ruling against Power Balance, who then had to offer an apology, retraction of their claims, and refund to anyone who wanted it.

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