Family Health Guide

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Vacccines: FAQs

Here’s an overview of some of the most common questions parents have about vaccines:

Can my child handle so many shots?
Vaccines are made of inactive or very weakened forms of a bacteria or virus. When they enter the body (either orally or through an injection), the immune system responds by creating protective antibodies. These antibodies then live in the body, providing protection against any exposure to the full-force version of the disease.

It’s easy to be scared off by the idea of injecting your child with even an extremely weakened or inactive form of an illness. But think of this: The average bacterium that causes a common ear infection is made up of about 3,000 immune components. Every dose of every shot that your child will receive between now and age 8, added together, contain only about 150 immune components, says Dr. Paul Offit, M.D., chief, Division of Infectious Diseases at the Children’s Hospital of Philadelphia. Even when your child gets many shots at once, it’s still just a tiny amount of the trillions of bacteria that her immune system deals with on a daily basis.

Do these diseases even still exist?
Unlike our parents and grandparents, we’re lucky to live in an era that has benefitted from a widely immunized population; we don’t see children that are paralyzed by polio or deaf because of the mumps. Many of the shots that our kids receive prevent diseases that many of us haven’t even heard of – diphtheria, anyone?

But when immunization rates drop, these deadly diseases can reemerge. That’s because vaccines aren’t 100-percent effective; on average about 95 percent of the protection comes from the vaccine and the remaining protection comes from living in a community where there are low rates of the disease. So for vaccines to keep a disease in check, most people in a community need to be immunized, so they’re not contracting and spreading the disease. This way, the few people that are not able to be vaccinated -- say, a child sick with leukemia, or a newborn who hasn’t had her shots -- will hopefully be protected by what’s called “herd” or “community” immunity.

There are parents who choose not to vaccinate their children based on either religious, philosophical or health objections, and the vaccines that are required to enter daycare or school vary from state to state. Many of these parents argue that their unvaccinated kids can benefit from herd immunity, too. Unfortunately, this isn’t a reliable way to protect your child. There have been deadly outbreaks of measles and pertussis in the United States in areas where vaccine rates have fallen. In Eastern Europe and Russia, where immunization has dropped, there have been tens of thousands of cases of diphtheria. For vaccines to work, a community needs to have high rates of immunization. Immunization not only protects your child, but your nieces, nephews, and neighbors, too.

Are vaccines safe?
Without daily reminders of the threat of these diseases, some people have started to fear the vaccines more than the diseases that they prevent. In recent years, a very vocal anti-vaccine movement has emerged, suggesting that vaccines are to blame for everything from allergies to diabetes to asthma to autism. While none of these claims have been proven true, there is still a growing community of scared parents who choose not to vaccinate their children based on this misinformation. In turn, these well-meaning parents end up putting their children at risk, and endangering their community as a whole.

As with any medical intervention, nothing is 100-percent risk free. But when you weigh the risks and benefits, the benefits of protecting your child against deadly diseases far outweigh the very remote risk that the vaccine may cause a reaction. The vast majority of children receiving an immunization will not have any reaction and if they do, it will be a minor one, like redness or soreness at the injection site. Keep reading for a review of the risks of reaction for every vaccine, as well as what you may have heard, and the bottom line as far as safety.

What is thimerosal?
Part of the controversy around vaccines stems from a preservative called thimerosal that was once regularly used in vaccines. Concerns arose because thimerosal is a compound that contains a form of mercury, known as ethylmercury. Another type of mercury, known as methylmercury,  can, in large doses (say, from drinking contaminated water or eating large amounts of contaminated fish), harm the brain development of a fetus or child. With the increased number of shots that children receive, some wondered whether children were being exposed to too much of this preservative. In particular, there were concerns that the preservative was to blame for increasing rates of autism, a behavioral disorder that has been on the rise in the U.S. in the past few decades.

As a precautionary measure, thimerosal was removed in 1999 from most vaccines (or reduced to trace amounts), with the exception of the flu vaccine, which is available without the preservative, though you need to request it from your doctor. But it’s worth understanding that while the methylmercury found in large fish can build up in the body and harm the developing brain of a growing child, the ethylmercury in thimerosal does not build up in the body. “It’s never been linked to any adverse effect,” says William Schaffner, M.D., professor of preventive medicine at Vanderbilt University Medical Center, in Nashville, TN. And autism rates in the US have continued to rise even after the preservative was removed from nearly all of the vaccines that children receive. In 2010, a U.S. court ruled that vaccines containing thimerosal cannot cause autism on their own. Read on for more about how the link between thimerosal and autism has been disproven.