Is It Dangerous that We Give so Many More Vaccines To Kids Today? No.

A couple of people on Twitter picked up on my vaccine post from last week, leading to the usual emails questioning vaccine use. A larger than usual number of them were irate at the increasing numbers of vaccines that we give kids today. They were sure that this must be dangerous. So I thought this might help; its adapted from my book:

Let’s start by recognizing that the human body has an enormous capacity to respond to potential threats. You are constantly exposed to foreign substances that stimulate your immune system. In a manuscript specifically designed to answer this question in the journal Pediatrics, Dr. Paul Offit and colleagues estimated that infants have the capacity to respond to about 10,000 vaccines at any one time. No vaccine could “use up” the immune system. In fact, estimates showed that if a child received 11 vaccines at one time, that might occupy about 0.1% of the immune system. You’d never notice that.

Moreover, this argument against vaccines assumes that the cells being occupied or destroyed in the vaccine response process are not replaced. You body is constantly making new cells, though, so this never occurs.

Another point, often overlooked, is that it is not the number of vaccines, or even the number of shots, that matters. It’s the number of antigens in those vaccines. An antigen is a molecule that the immune system recognizes. The immune system decides whether any molecules it comes in contact with belong to itself or whether they should be treated as foreign intruders. Vaccines are specifically designed to show the immune system an antigen that belongs to a particular disease so that the immune system will be armed and equipped to fight against that disease if it sees it again. Advances in technology have helped scientists create vaccines that contain fewer and fewer antigens and yet achieve a good response from your immune system. Back in the day, a single smallpox vaccine had over 200 different proteins in it. In the 1980s, the 7 vaccines routinely given to children contained more than 2000 antigens. More recently, the 11 vaccines in the currently recommended schedule have only about 125 antigens in all. Even though it seems like a lot of shots, the immune system has to do far less work to respond to the current set of antigens than children’s immune systems have had to do over the past 30 years.

This is confirmed in studies. Research has shown that giving vaccines alone or in combination does not affect their ability to achieve a response. A trial comparing the effectiveness of the MMR and chicken pox vaccine given together and alone showed no differences in their effectiveness. The immune system responded how it should whether the shots are given separately or given at the same time. Another study compared the effect of giving MMR, DTP and polio boosters at the same time to giving the vaccines individually, one after the other. The vaccines were just as effective when they were given at the same time as when they were given individually. On other words, the immune system responded just as well when the shots were combined together. The same result was seen when looking at adding Hepatitis B vaccines to other vaccines in infants. Your body can easily handle the load.

If you remain concerned that giving a vaccine weakens the immune system, studies show us this is not the case. A study of almost 500 children in Germany found that infants who received vaccines in the first three months of life had less, not more, illness from germs. They had fewer illnesses from both germs that were included in the vaccines and from germs that were not covered by the vaccine. The babies’ immune systems were working fine! In fact, the immune systems in the children getting the shots may have even been working better. Another study of children in Alaska receiving the DTP vaccine found no relationship between getting vaccines and increased risks of other infections.

And before anyone mentions autism, please go read this.

Remember, we don’t want to poke your children any more than you do. But they really do benefit from those vaccines.


Extracted material from DON’T SWALLOW YOUR GUM! by Aaron Carroll, MD and Rachel Vreeman, MD copyright © 2009 by the author and reprinted with permission from St. Martin’s Griffin, an imprint of St. Martin’s Press, LLC

[Cross-posted at The Incidental Economist]