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The vaccine schedule is safe and effective

July 02, 2014

Pediatricians often hear from parents that they are worried about giving too many vaccines at one time and “overloading the immune system” of their infant. As a result, parents ask to “spread the vaccines out more.” As pediatricians, we know that the vaccine schedule outlined by the Centers for Disease Control and Prevention (CDC) and recommended by nearly all pediatricians is safe and effective. We don’t understand how some rogue physicians and some well-meaning, but ignorant public figures can contradict good science and suggest that the vaccine schedule that we use is unsafe.

All scientific evidence says that the vaccine schedule

is indeed safe and very effective.

Many people draw the conclusion that it must be dangerous to give vaccines all at once. But in fact, that could not be further from the truth. There are very specific reasons that we use each vaccine the way that we do, both when they are started, and how and when they are repeated. What I will give you in this post and in subsequent posts is hopefully a clear, understandable explanation of the design of the CDC’s recommended immunization schedule.

The Hepatitis B Vaccine

The hepatitis B vaccine is the one immunization that we routinely give as soon as a baby is born. This is for two reasons. First, it works that early. Newborns’ immune systems are already up and running and are able to respond to the hepatitis B vaccine and make antibodies right away. This is a very fortunate thing, as many of our vaccines don’t work in a newborn body. What we know about hepatitis B is that almost all cases in children are caused by spread from an infected mom during birth. Many moms who are carriers of hepatitis B are missed during pregnancy or in the hospital, either due to lack of prenatal care, lab error, or lack of communication. The amazing thing is that the one dose of hepatitis B vaccine, if given right after birth, is essentially perfect in preventing infection of the newborn. The birth dose of hepatitis B vaccine saves lives every day. The other nice thing about that vaccine is that there are essentially no relevant side effects, not even fever or discomfort.

The Two-Month Wellness Visit

We start our next routine vaccines at the two-month wellness visit. When we immunize we want to be sure that enough of mom’s antibodies are out of the newborn’s system and that the newborn’s immune system has matured enough to respond to our vaccines. We know that in the first month or more, some of the vaccines don’t work well yet. However, by six to eight weeks they work very well; this is why the DTaP, Polio, HIB, rotavirus, and pneumococcal vaccine series start when they do.

This is NOT because the immunizations would

“overwhelm” the immune system if given earlier.

They just would not be effective.

Of note, the most common and relevant side effects of the vaccines given to infants are a little bit of diarrhea or throw-up from the rotavirus vaccine, and maybe a little fever, fussiness, or local reaction in the thigh muscle for the others.

The MMR Vaccine Controversy

The MMR (measles, mumps and rubella) vaccine is one that has received a lot of attention since it was wrongly accused of causing autism.

In fact, vaccines have clearly and repeatedly been shown

not to cause autism or other developmental disabilities.

And yet, many parents still believe that we wait to give the MMR until a year of age because it might be harmful if given earlier. They then wonder if waiting even longer might be even better. The problem is that the younger you are when you get the measles, the sicker you get and the more likely you are to die. Our goal with the MMR is to protect small children as young as we possibly can, and to reduce the spread of disease in our communities.

We would give the MMR at two months of age with the other vaccines if it would work! However, the scientific dance that we have to do with the timing of the MMR is based upon the fact that measles antibodies from mom, shared with the baby through the placenta, stick around for a very long time. If those antibodies are still in the baby’s body when we give the vaccine, mom’s antibodies attach to the vaccine inside the baby’s body, thus hiding the vaccine from the baby’s own immune system. This “masking” makes the vaccine ineffective in getting the baby to produce antibodies; the vaccine just does nothing for the baby. That is why we wait until one year of age, so that we are sure that in most cases maternal antibodies have dropped to a low enough level to allow the baby’s immune system to see and respond to the MMR.

An interesting little side note: we immunize against rubella, or German Measles, not because it is a terrible disease. In fact, it is a really minor little viral illness that causes a few days of fever and a minor rash. However, if a pregnant woman is not immune to rubella and catches it while pregnant, the fetus can be devastated. Congenital rubella is a horrible thing. This is the whole reason we immunize against rubella. By eliminating rubella in the community, we protect everyone’s babies before they are born from a life of suffering.

I hope that my insight has helped give you a better understanding of why we give certain vaccines when we do. We’ll continue this conversation in future posts, so stay tuned!

If you have any questions about vaccines or the vaccine schedule, leave a comment below.