Children in the United States today routinely get vaccines that protect them from more than a dozen diseases, including measles, polio, and tetanus. Vaccines help make children immune to serious diseases without getting sick first. Without a vaccine, children must actually get a disease in order to become immune to the germ that causes it. Christine Ziebold, MD, pediatric infectious disease specialist at University of Iowa Children’s Hospital, located in UI Hospitals and Clinics, talks about childhood vaccinations, and why they are so important:

With diseases like polio or even measles at their lowest level in history, why is it still important to immunize children against such diseases?

We vaccinate against these so called “childhood diseases” a name that seem to belittle their magnitude because they are very serious illnesses. While they are less and less visible, they have not been eradicated—that is they haven’t gone forever—not in this country or other countries which we’re connected to by travel and migration. Most of these childhood diseases never will be eradicated, so it is important to keep vaccinating. If enough people are immune to a disease, it cannot spread, which is also called herd immunity. We have universal vaccination programs which involve everyone and their success depends upon participation. Imagine a brush land or a forest. If enough dry grass or dead brush is around, a fire can spread easily. If it all is living green and moist with creeks and intact wetlands, the fire can’t spread. Vaccines stimulate the body’s immune system to produce defenses against a particular disease without the body actually having to go through the disease.

Is there a specific reason several injections are given together at some pediatric visits?

The reason is that there are so many vaccines we want children to get, especially a baby in the first year—that we immunize against nine illnesses. There are only so many opportunities exist for seeing the child—between four and five well-child visits. Fortunately, many of the vaccines are already “combination vaccines,” that is, one injection combines several vaccines against several diseases like DTP (diphtheria, tetanus and pertussis) or MMR (measles, mumps, rubella) to reduce the number of injections a baby has to endure. Every year we get more “combination vaccines,” so that’s good. Babies can handle vaccinations against a lot of different diseases at the same time. Unfortunately very few vaccines can be swallowed, which would be the easiest way. But researchers are working on putting vaccines into banana or potatoes.

Parents may hear and have concerns about vaccinations containing thimerosal, a derivative of mercury, that some believe has links to increased autism cases. Do parents risk their child’s health by having them vaccinated?

No, they don’t. We now know that there is no link between autism and thimerosal. The cause of autism remains unknown and so, because of this quandary, all kinds of associations have been speculated. Thimerosal, which is essentially a type of mercury—ethylmercury—has been used as a preservative in vaccines since the 1920’s. It has been suspected to be linked to autism, since mercury is toxic at very low levels to nerve cells, including the brain, so we call it a “neurotoxin.”

Some aspects of autism can look similar to mercury poisoning. Because of that, and being safe rather than sorry, in 1999 Thimerosal was removed from children’s vaccines. It is now present in only trace amounts in several vaccines that one can look up on the Web. The one prepared as a multidose vaccine for flu is one example.

A final proof that there is no link between autism and Thimerosal has come over time because autism numbers have not declined in the U.S. since Thimerosal was removed—something that other countries have also reported. This should settle the debate.

Another concern some parents may have are aluminum salts, even though they have been added to vaccines since the 1920s. What are the concerns with aluminum regarding vaccines?

Aluminum for some people is the new mercury or Thimerosal. It’s only recently been brought up as a concern by some parents. And I stress some parents, because most have no concerns with it.

Aluminum is added to vaccines to aid in the immune response, which in the technical lingo is “adjuvant.” In very rare cases, it has been reported to cause like an overreaction, e.g. a persistent swelling at the injection site, which recurred when they got a vaccine containing aluminum again. This is similar to a contact allergy. But this is very rare.

The other concern has been that aluminum is potentially also a neurotoxin. It’s been mentioned by some in the same breath as mercury and having similar effects and symptoms, and has been purported to cause Alzheimer’s.

But there is no evidence for aluminum causing serious health problems in children. Unlike mercury, children are exposed to aluminum through many sources and at comparatively large amounts like in anti-caking agents that are in salt, baking powder, antacids (in large amounts), and even cookware. Health effects to these exposures have not been observed.

There are concerns with parents who do not want their child vaccinated and, in some cases, are willing to home school their children to avoid mandatory vaccinations for children entering school. What advice would you give to these parents who are very reluctant to immunize their child?

The risks are first and foremost that their child remains unprotected. Sometimes this may be working out fine, and the child may overcome the infection without serious complications, but sometimes the child may get extremely ill, and even now may sometimes die of a vaccine-preventable disease.

In the case of bacterial infections, we try to prevent them with vaccinations like pneumococcus or the staph aureus, which follows the flu (influenza). It may be difficult to treat the child with antibiotics because bacteria get more and more resistant. And some illnesses that are postponed into adolescence and not dealt with earlier are much harder to deal with. For example chicken pox or mono. There is also the risk for the community as a whole, as we do not exist alone. Every time someone has a vaccine-preventable disease, it’s a win for the bug, it’s a path for the fire to spread, so to speak. So let’s keep the vaccines working and have everybody immunized.

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Christine Ziebold, MD

University of Iowa Children’s Hospital