Does the Mercury in Vaccines Cause Autism? What's the Safest Immunization Schedule for Infants?

With the recent news of President-Elect Trump's talks with Robert F. Kennedy, Jr. to potentially head a new commission on vaccine safety and scientific integrity, many in the scientific and healthcare communities are understandably rattled. Kennedy is a well-known skeptic of vaccine safety, and has previously described the vaccine/autism allegations as such:

“They get the shot, that night they have a fever of a hundred and three, they go to sleep, and three months later their brain is gone. This is a holocaust, what this is doing to our country.”

Source: James Gathany, Judy Schmidt, USCDCP

Mercury is toxic to the human body. It's important, however, to understand how the mercury present in immunizations is different than the mercury in, say, the scary old thermometer in your medicine cabinet.

Thimerosal is a vaccine preservative. Since the early 20th century, small amounts of thimerosal have been used in vaccines to prevent the growth of fungi and bacteria. Thimerosal is mainly composed of ethylmercury. When we hear concerns of mercury toxicity (for example, with the consumption of fish), we are primarily concerned about the compound methylmercury.

Methylmercury (left) and ethylmercury (right). Image source: Wikimedia Commons (public domain)

Ethylmercury is metabolized and excreted by the body much faster than methylmercury (half-life of 1 week vs. 6 weeks), meaning methylmercury is more likely to "build up" in the body. You consume higher, longer-lasting, more concerning doses of mercury when you eat a serving of fish than when you get a vaccine.

Many independent epidemiological studies over the last two decades have concluded that the low doses of thimerosal in vaccines are not harmful to infants, and the compound is not present in routine childhood vaccination schedules in the U.S., E.U., and several other countries. All this said, the current scientific consensus is that there is no compelling evidence linking vaccinations and autism; mercury poisoning does not resemble autism, and rates of autism diagnosis continue to rise despite the removal of thimerosal in many vaccines.

Furthermore, there is no evidence to suggest that the American Academy of Pediatrics' recommended immunization schedule is harmful, or that young children's bodies can't "handle" it. Spacing out vaccines only increases the amount of time by which children are vulnerable to contracting vaccine-preventable diseases. The parents' choice to delay their children's immunizations is what caused the measles outbreak in Disneyland in 2015, with nearly 150 cases.

It's estimated that the MMR (measles, mumps, and rubella) vaccine has saved 17.1 million lives worldwide since 2000. Herd immunity is important for the health of the entire community, as not all children can be vaccinated or will respond satisfactorily to immunizations.

Further reading:

• Centers for Disease Control: Understanding Thimerosal, Mercury, and Vaccine Safety
• Centers for Disease Control: Immunization Schedules for Infants and Children
• Dorea et al.: Toxicity of ethylmercury (and thimerosal): a comparison with methylmercury (J Appl Toxicol 2013; 33:700-11)
• Flaherty: The vaccine-autism connection: a public health crisis caused by unethical medical practices and fraudulent science (Ann Pharmacother 2011; 45:1302-4)

Why yawning is contagious

Check out the woman on the right and try not to yawn. Go on, give her a good ten seconds of your time. In the spirit of A Christmas Story, I triple-dog dare you. Really—try your absolute hardest not think about yawning as you read this post! C'mon, you know you can do it—you've been dared before, and you always fail miserably. NO YAWNING!

Chances are you've already let out an extended, eye-moistening, feel-good yawn or two at this point. I've personally counted six of my own since starting this post.

We've all heard that "yawning is contagious"—but why? In this busy world, we don't sleep as much as we should. Gallup Polls in recent years have found that 56% of Americans report drowsiness as a daytime problem, and 34% of us are "dangerously sleepy." Does seeing someone yawn remind us that we, too, are exhausted are must follow suit?

That may be part of it, but the true reason may go much deeper. As it turns out, yawning may have ancient roots in social bonding.