Vaccines for infants and young children

In primary care pediatric practice, I find that many parents are overwhelmed and not sure why vaccines are needed, how they work or what to expect as far as side effects. It can be confusing even for those experienced parents, but I hope I can help!

How do vaccines work? In general, when a bacteria or virus (the antigen) enters the body, the immune system recognizes it as something foreign. The body’s immune system makes specific components called antibodies, which help “remember” the infection and fight it off in the future. This happens when we are exposed to illnesses, but it also is why vaccines can be used to give immunity to serious illnesses. Vaccines contain weak or dead versions of the antigen, which prompt our bodies to make antibodies against that specific virus or bacteria. These antibodies act as an “army in waiting” to fight off the illness if you come in contact with it, meaning that you don’t become sick with the illness at all, or if you do contract it, it will generally be very mild. Another important benefit of vaccination is that there is less underlying illness in the community, so that children who are too young or unable to be vaccinated will also be less likely to contract the illness.

Why do my kids need so many booster shots? It seems like just one shot should protect your child, right? However, the immune system works in very complex ways, well beyond the scope of this blog. Some vaccines give lasting immunity for many years with just one shot. Others need multiple doses because the body clears the antibodies more quickly. The immune system responds differently to some illnesses in a baby as compared to an adult. The infant and toddler period is the most vulnerable time for contracting certain illnesses, such as HIB and Pneumococcus, and therefore, most critical to be vaccinated on time. Getting boosters helps “remind” our immune system to be ready to fight off illness.

What side effects are common after vaccines? In my daily practice, I think this is probably the most common question that I get. As a parent of two preschoolers, I absolutely understand this concern. Immunizations do have some common side effects just like any other medication. The ones most commonly seen are tenderness at the injection site, fever and fussiness. Even though it is hard to see your child fussy, you can also see it as a positive thing because it means your child’s immune system is doing the job of fighting off the antigen. Severe reactions to vaccines are very, very rare. You should talk to your pediatrician to find out what they recommend for these side effects. Most of the time a cool compress will work. I recommend parents avoid giving pain relievers unless the child is very fussy, because there is some evidence that pain relievers might reduce the effectiveness of the vaccine itself. In general, the common side effects last only a day or two.

Is my child up-to-date on their shots? It is helpful to ask your child’s pediatrician at every sick visit if they are up-to-date on their well checks and immunizations. It is easy to miss an appointment or forget to call and schedule a well check. Young children are due for vaccines at birth, 2, 4 and 6 months, and then again at 12 months, 15 months and 18-24 months. Then they will get booster shots again before kindergarten at 4-5 years old. Don’t forget that yearly flu vaccine as well! It is also a great idea to print out a recommended shot schedule to keep at home and check off the shots as your child receives them to make sure they are on time. Click here to download one of these forms.

Dr. Mary T. Martin is a pediatrician with Pediatric Associates–Easley.

Last reviewed 08/2018
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