Fact-checking vaccines and measles

A recent measles outbreak at California’s iconic Disneyland put the spotlight on a disease many people had probably thought was on the verge of eradication.

But it also instigated debates about the safety of the measles vaccine — which the scientific community and the vast majority of the population consider long-since settled — and whether it should be mandated for children.

Sen. Rand Paul, R-Ky., straddled both sides when he endorsed vaccines as safe but suggested they should be voluntary during a Feb. 2 interview on CNBC.

He then added a perplexing nod to long-standing myth: "I have heard of many tragic cases of walking, talking normal children who wound up with profound mental disorders after vaccines." Paul later clarified that he didn’t mean to say that vaccines caused the disorders, just that they sometimes happened around the same time.

There’s a lot we don’t know about what causes autism, but doctors we spoke with said you can definitely rule out vaccines. Decades of epidemiological research has demonstrated autism rates do not increase when vaccines are introduced to a population. And biologically, no lab work has demonstrated a way for vaccines to cause autism.

There are instances when a child develops normally before experiencing a drastic regression that results in severe mental impairment. It’s a type of autism known as childhood disintegrative disorder and it affects about 1 in 10,000 children. In some instances — but not most — this change can occur around the time children are receiving vaccinations. The evidence shows that’s coincidental.

"I’m a parent of a child with autism myself, and I completely understand a parent’s fear, and I don’t frown upon any parent who is concerned about it," said Kevin Pelphrey, director of the Child Neuroscience Laboratory at Yale. "But as a scientist, I absolutely know vaccines did not cause my daughter’s autism, and they do prevent diseases that kill children."

Just how settled is the science on vaccines and autism?

"Five years ago the science wasn’t even as certain as it is today," said Fox News host Megyn Kelly. "It is very certain today." We rated her statement True.

Five years ago, a widely debunked and criticized paper on vaccines and autism was formally retracted by the British medical journal The Lancet. The paper, originally published in 1998 by Andrew Wakefield and a dozen colleagues, claimed to show a link between the MMR (measles, mumps, rubella) vaccine and autism. But the study included only a small number of actual cases — about 12 children. It later came out that some of the work was fabricated, and that Wakefield was paid by lawyers for parents of children in the study.

But the Wakefield study had such a high profile that it spurred further rounds of research. In 2001, the Institute of Medicine published a report that found no evidence of an association between the vaccine and autism. In 2004, the institute conducted another review.

The institute said, "14 large epidemiological studies consistently showed no association between the MMR vaccine and autism."

Retracting the paper was the final nail in the coffin of a discredited report.

Officials warn that unfounded theories about the vaccine could lead to fewer immunizations, which would pose a significant public health risk and the return of a disease that was nearly eliminated.

One problem the measles poses is that it’s very contagious.

CNN senior medical correspondent Elizabeth Cohen said it doesn’t even take a kiss to spread it. "It’s airborne," she told Anderson Cooper on Feb. 2. "If someone is in a room that has measles and leaves and you walk in two hours later, you could get measles from that person."

She’s right. The measles virus stays in the nose and throat mucus of someone who has the infection and according to the Centers for Disease Control and Prevention, the measles virus can live for up to two hours on a surface or in an airspace where the infected person coughed or sneezed.

The disease is so easy to catch, the CDC adds, that if one person catches it, a whopping 90 percent of people who are not immune (that is, did not have the vaccine due to a weak immune system, age or personal choice) but are the infected person will also become infected. We rated Cohen’s claim True.

In addition to being easy to spread, the effects of the disease can be quite serious.

Celine Gounder, a doctor and frequent medical pundit, took particular issue with Paul’s comment because of his medical background.

"Frankly, Rand Paul as an ophthalmologist should be out there saying measles is one of the most common causes of child blindness worldwide," Gounder said. "And as an eye doctor, he should be advocating for measles vaccination for that reason."

She’s right. In the developed world, measles don’t typically lead to blindness. But in Africa and Asia, where measles vaccinations are less prevalent, the disease leads to 15,000 to 60,000 cases of child blindness each year.

That’s because measles infection can reduce vitamin A levels. The cornea, the front transparent layer of the eye, requires vitamin A to work. And the retina, which is the back layer of the eye that receives visual images (like the film in a camera), requires vitamin A in order to allow us to see at night. So the vitamin A deficiency brought on by measles causes ulcers on the cornea that can result in blindness.

So the distinction "worldwide" is a critical one, but nonetheless we rated Gounder’s statement True.

A common misperception about vaccines is that it contains mercury. The anti-vaccination community often trumpets this point as evidence that unnatural, poisonous ingredients that can cause harm are used in these shots.

One widely circulated Internet post from 2012 by Mike Adams, editor of NaturalNews.com, repeated that childhood shots contain mercury, a powerful neurotoxin with no safe level of use.

"Doctors who inject children with vaccines are delusional," Adams concludes. "They are practicing a medical holocaust against humanity."

PolitiFact Georgia found that ethyl mercury, a component in the vaccine preservative thimerosal, used to be put in vaccines. However, after Wakefield’s erroneous study created an international panic, the Food and Drug Administration in 1999 decided to remove thimerosal from all childhood vaccines. This despite the fact there was no other evidence linking the preservative to autism.

Adams also confuses the issue with the interchangeable use of the term "mercury" for both ethyl mercury and the more problematic methyl mercury.

Ethyl mercury, used in trace amounts in vaccines before 1999, is easily expelled from the human body in small quantities. Methyl mercury is the compound found in fish and water, which builds up because the body can’t easily expel it.

So the mercury included in the shot was not problematic, nor is it even used in the series of shots recommended for childhood immunization. Pants on Fire!

How did the outbreak at Disneyland even occur? It’s still a mystery but conservative talk show host Rush Limbaugh has a theory: "Barack Hussein Obama and his open borders immigration policy, which opened the southern borders to children sick, healthy, you name it, poor, ill-educated, just tens of thousands of kids flooded the southern border all of last year.

"They were never examined before they got here. They were never examined after they got here and quarantined if they had a disease. They were just sent out across the country. Many of them had measles."

There’s no evidence of this. The children who came in from Central America were examined and vaccinated as part of a standard routine. What’s more, vaccination rates in the countries from which they came are on par with the United States.

It was a claim with no basis and we rated it Pants on Fire.