I know this is old news – or at least it should be – but it bears repeating, especially as we are in the midst of a resurgence of measles. There is no link between the mumps, measles, and rubella vaccine (MMR) and autism, or any neurological disorder. A new study confirms this lack of association. This should go a long way to reassure the vaccine hesitant that the MMR vaccine at least is safe and should not be avoided.

This is a Danish study, and the largest study of the MMR vaccine and autism to date – “657,461 children born in Denmark from 1999 through 31 December 2010, with follow-up from 1 year of age and through 31 August 2013.” They found:

During 5,025,754 person-years of follow-up, 6517 children were diagnosed with autism (incidence rate, 129.7 per 100,000 person-years). Comparing MMR-vaccinated with MMR-unvaccinated children yielded a fully adjusted autism hazard ratio of 0.93 (95% CI, 0.85 to 1.02). Similarly, no increased risk for autism after MMR vaccination was consistently observed in subgroups of children defined according to sibling history of autism, autism risk factors (based on a disease risk score) or other childhood vaccinations, or during specified time periods after vaccination.

Overall there was no association between getting the MMR vaccine and later being diagnosed with autism. Further, there was no correlation when looking specifically at children who have a sibling with autism, and therefore might constitute a susceptible subpopulation. Further still, there was no clustering of autism diagnosis following the MMR vaccine administration, as might be expected if there was a causal link. This is a very large study with an adequate study design, so that if there were any increased risk of developing autism from the MMR vaccine we should be seeing it in this data – and we don’t.

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A new study published in the current issue of Pediatrics looks at the association between mainstream media coverage of the claim that there is a possible correlation between the mumps measles rubella vaccine (MMR) and autism and the rate at which American parents refused the MMR vaccine for their children. The results were a bit surprising.

Smith et. al. used the LexisNexis database to track media reports of Wakefield’s initial study showing a possible connection between MMR and vaccines (the study was later discredited, and to date there is no evidence to support such a connection). They compared this to data reporting the incidence of parents refusing just the MMR component of the routine childhood vaccine schedule (so-called selective MMR nonreceipt). Their hypothesis was that media coverage would correlate with an increased incidence of selectively refusing the MMR. But that is not what they found.

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RFK Jr., who is now running for the Democratic presidential nomination, is anti-vaccine. He will vehemently deny this, but I don’t buy it for a second. He is simply playing the, “I’m not anti-vaccine, I am pro-safe vaccine” gambit, which is disingenuous and always has been. We have been covering this topic for years, and David Gorski did a recent excellent review of this at SBM. You can’t claim not to be anti-vaccine, and then defend a long list of anti-vaccine tropes.

RFK has apparently been avoiding his views on vaccines on the campaign trail, but it always seems to come up. On the Joe Rogan podcast RFK found what he must have thought was a friendly environment, and felt free to repeat is claim that vaccine cause autism. This is a topic I have been covering for two decades – vaccines do not cause autism. But let’s do a quick review of this harmful claim.

This first appeared in the 1990, when the anti-vaccine movement hit upon the increase in autism diagnoses as a new tactic. They start with the assumption that all bad things that happen to children are caused by vaccines, so obviously they must also be causing the rise in autism. When Andrew Wakefield came out with his fraudulent and now retracted study claiming an association between the MMR vaccine and autism, he became an instant celebrity of the anti-vaccine movement. Trouble is – the MMR vaccine does not cause autism. Wakefield, it turns out, had a patent on an alternative vaccine and was trying to torpedo the competition. But the anti-vaccine movement does not let science, evidence, or basic logic get in their way. So they simply moved over to a vaccine ingredient, thimerosal, which is a mercury-based preservative.

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In the US we have semi-compulsory vaccination. Keeping up to date on the vaccine schedule is required in order to attend public school. However, families always have the option of attending private schools, which can determine their own vaccination policy, or they can home-school. Also, each state can determine its own exemption policy. Medical exemptions are uncontroversial – if you medically cannot get a vaccine, that is up to your doctor, not the state. However, some states have religious or personal (philosophical) exemptions. These have been under increasing scrutiny recently.

Other countries have different systems. In the UK, for example, there is no compulsory vaccination to attend school.

These policies are all being reexamined in the wake of the burgeoning anti-vaccine movement and the resulting return of previously controlled vaccine-preventable illnesses. Let’s take measles, for example. As you can see by the chart, measles cases have increased by greater than 20 fold from 2010 to 2019 in the US. But if we pull back even further, in 1980 measles caused 2.6 million deaths worldwide, with cases in the US alone measured in the hundreds of thousands. By 2000 routine use of the MMR vaccine had prevented an estimated 80 million cases of measles.

Also by 2000 measles had been eliminated in the US – that means there was no circulating virus in the wild. All cases came from outside the country. Outbreaks were also very limited, because there was no fertile ground for the virus to spread. The antivaccine movement has changed that.

The rate of children getting MMR has not changed much in the US due to compulsory vaccines, ranging from 90-93% over the last two decades. It has dipped to around 91.1% recently, but the overall number remains high. However, this statistic hides what is really going on. Vaccine refusal clusters, by neighborhood and by school. If a private school does not require compulsory vaccination, then anti-vaxxers will cluster there. These pockets of very low vaccination rates then serve as potential locations for outbreaks, and that is exactly what happens. In recent years these outbreaks have been large enough to spread into the general population.

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A new report looking at vaccine confidence in the EU shows some troubling trends. Belief in the safety and effectiveness of vaccines seems to be very regional. We see this in the US as well as Europe. In this survey they found:

The results of the survey suggest that a number of member states – including France, Greece, Italy, and Slovenia – have become more confident in the safety of vaccines since 2015; while Czech Republic, Finland, Poland, and Sweden have become less confident over the same period.

In some countries anti-vaxxers have a stronger foothold, and are actually decreasing acceptance of vaccines. But there are two other trends that are more disturbing. First, in the countries with decreasing vaccine acceptance there is high levels of vaccine skepticism among general practitioners.

While GPs generally hold higher levels of vaccine confidence than the public, the survey found that 36% of GPs surveyed in Czech Republic and 25% in Slovakia do not agree that the MMR vaccine is safe and 29% and 19% (respectively) do not believe it is important.

Those are shockingly high numbers for physicians. This is one of my greatest fears about the advance of alternative medicine and anti-scientific medical views – that they will affect the medical profession itself. Once unscientific ideas creep into the culture of medicine, the game is all but lost. This is why teaching pseudoscience in medical school is such an alarming problem. In this survey, the countries with higher levels of GP vaccine skepticism, had higher levels of public skepticism and lower levels of vaccine compliance.

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There is a strong scientific consensus that vaccines generally are an effective approach to preventing infectious illness. The vaccine schedule is arguably the most effective and cost effective health promotion intervention ever devised. Vaccines are a public health home-run.

How, then, to explain the anti-vaccine movement? The anti-vaccine movement is based mainly on science-denial and conspiracy theories. This means they spread a lot of misinformation – the bits of misinformation become articles of faith, and any evidence to the contrary is denied or dismissed.

I recently received the following question, which is framed as a sincere question, but I have my suspicions that it may not be:

Have just read your article.

I fully agree that herbal medicines/substances should have full clinical trials but can never find anyone able to refer me to
any clinical trials placebo versus substance to be tested on vaccines.
So wondered if you could help me as you are obviously a man of science.
Would be very grateful as there must have been clinical trials sometime.
Even my Dr draws a blank.
Many thanks
Pam

Pam may simply be the victim of anti-vaccine propaganda, and may simply lack all Google skills, but the phrasing strongly suggests an anti-vaxxer goading a skeptic with a “gotcha” question. Since this is a common anti-vaccine trope, let me dispel it once again.

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In the US routine childhood vaccination is required for entry into public school, and in some states even private school. This is a reasonable public health policy. Vaccination not only protects the individual against common infectious diseases, but when enough people get vaccinated this creates community immunity (often referred to as herd immunity) which protects everyone.

Any parent knows first hand that children are seething vectors for germs. Their concept of hygiene, generally speaking, is often not the same as the average adult. Put a large group of children together in a close environment like a school, and you have basically created a disease factory.

Further, some children cannot be vaccinated for medical reasons. They may have a chronic illness that makes their immune systems too weak to handle the vaccine, or they have an intolerance to vaccines. For these children, if they want to attend school, their only protection is the community immunity that results from all the more healthy children being vaccinated.  Continue Reading »

This has been a typical saga, one we have seen played out many times. An organization (company, institution, etc.) provides a venue for an irresponsible anti-science article, speaker, or film. There is then a public outcry that the venue is being exploited to promote pseudoscience. The organization initially defends their decision, then reconsiders. The author, speaker, director then cries “censorship.”

It’s a predictable script.

Recently the Tribeca Film Festival announced its list of movies it will be screening this year, and among them was Vaxxed: From Cover-Up to Catastrophe, a movie perpetuating the idea that the Center for Disease Control (CDC) is covering up data that shows a link between the MMR vaccine and autism.

Orac discusses the content of the movie in detail, but here is a quick summary. The movie is produced by Andrew Wakefield, the disgraced struck-off British doctor who published a study in the Lancet claiming evidence for a connection between MMR and autism. The paper was later retracted and found to be fraudulent.

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I gave a talk on the vaccine controversy over the weekend. I was not surprised that a couple of audience members had a lot of questions taken directly from anti-vaccine propaganda sites. What was interesting was that they were still pushing the idea that thimerosal, a mercury-based vaccine preservative, is linked to autism.

The reason this is interesting and illuminating is that the thimerosal hypothesis is not just mostly dead, it is most sincerely dead. It is pushing up the proverbial daisies.

A Brief History of Thimerosal

Thimerosal was developed as an organomercurial anti-microbial agent shortly after World War I. It was soon discovered that it has great anti-microbial properties and was well tolerated when injected into rabbits or rats even at high doses. This made it superior to anything else available at the time.

Bacterial contamination was a serious problem for vaccines in the first half of the 20th century. Thimerosal in tiny doses, well below safety limits, proved to be an effective agent for preventing contamination. By the 1940s thimerosal was being added to several vaccines for this purpose.

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A new study has been published in PNAS exploring methods for changing the attitudes of those who are anti-vaccine. The results differ from a previous study published last year in Pediatrics. Let’s explore their methods and results.

Both studies questioned subjects about their attitudes toward vaccines and their willingness to vaccinate their children. The Pediatrics study was web-based and recruited 1759 parents. They divided them into four groups:

(1) information explaining the lack of evidence that MMR causes autism from the Centers for Disease Control and Prevention; (2) textual information about the dangers of the diseases prevented by MMR from the Vaccine Information Statement; (3) images of children who have diseases prevented by the MMR vaccine; (4) a dramatic narrative about an infant who almost died of measles from a Centers for Disease Control and Prevention fact sheet; or to a control group.

The PNAS study was in person, but only recruited 315 subjects. They divided people into three groups: 1) given information debunking vaccine myths, 2) told about the risks of measles and shown graphic images, 3) control group given information unrelated to vaccines.

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