Pediatricians tell you over and over that you need vaccines, or immunizations, that they are important, and that we can give several of them at a time.  What we don’t always tell you is how they work, or why it’s important to not have certain diseases, or why it’s okay to give multiple shots at once. For the second question, I’ve been occasionally posting on the various diseases.  For the other questions, here are some simple answers.

How do vaccines protect my child?

There are two basic ways vaccines protect.  The first is the active immunity gained by the person the shot it given to.  With this, a small amount of bacteria, virus, or toxin is injected into a person instead of letting them get the illness.  Then, the immune system is able to remember this and recognize it the next time the body encounters it so it can make a quicker response.

The second is herd immunity.  This is when someone is protected from an illness because the people around them have immunity to it.  Think of a wagon train circling up to protect against robbers. This is especially important for those who can’t be immunized, such as people with cancer or bad immune systems.  

Why do some vaccines have to be given more than once?

This depends on how the vaccine is made and how, exactly, it interacts with the immune system.  There are a few different reasons a vaccine is given more than once. First, especially in early infancy, it takes several doses to make an appropriate immune response.  Second, sometimes the vaccine efficiency wanes after several years and it has to be redosed – such as the tetanus vaccine. Third, sometimes the first dose gets most people, but two doses covers a better percentage of people.   

Won’t they get a better immune response from the actual disease instead of a vaccine?

Sometimes that’s true.  There are a lot of times that the immune system reacts more to an actual infection, it’s one reason we give more than one dose of most vaccines.  However, actually getting the disease puts your child at risk of the disease and its complications. Even something like chickenpox, that most people think is not harmful, leaves scarring on most people.  Some people with chickenpox develop lung or brain infections, as well. 

Sometimes it’s not true.  Surprisingly, there are a few vaccinations that give a better immune response than the actual infection.  And, in at least one case – tetanus – having the infection gives you no immunity.  

Are vaccines safe?

Yes.  First, when vaccines are being developed, they go through a rigorous series of tests before they are ever considered for being put on the market.  Then, once it’s ready to go, the Advisory Committee on Immunization Practices (ACIP) that determines which vaccines go on the schedule and when go through a lengthy process that determines if a vaccine is safe, effective, and if it’s even needed.  Also, as a vaccine is produced and sold, the manufacturer tests the various lots as they are produced. The FDA not only watches the manufacturer’s testing, but also regularly inspects the plant to make sure it is safe and working properly.

Finally, the FDA and the CDC monitors vaccine safety in a variety of ways.  The Vaccine Adverse Event Reporting System is a reporting system for adverse events with vaccines.  Anyone can make a report – doctor, vaccine company, a patient – which is then evaluated for possible further investigation.  The resulting database is open to everyone. The Vaccine Safety Datalink and the Post-Licensure Rapid Immunization Safety Monitoring makes it possible for scientists to actively monitor vaccine safety.  Then the Clinical Immunization Safety Assessment Project between the CDC and certain medical research centers provides answers to tricky safety questions for doctors, and conducts studies on the safety and efficiency of vaccines.  The ACIP can take information from these groups, and change their recommendations as needed to keep the public as safe and healthy as possible.

Is it bad to give too many vaccines at once?

No, in fact it is better for the baby because when they get their vaccinations at the correct time they are better protected from diseases that can hurt them.  Studies have been done on spreading out the vaccination schedule, but the only thing proven was that it kept the baby susceptible to diseases longer than they would have been with a regular schedule.

You don’t have to worry about the baby’s immune system being overwhelmed with the multiple antigens in the shots even when we give several at a time.  The number of antigens in shots pales in comparison with the thousands of antigens a child is exposed to every day in the foods they eat, the air they breathe, and what they touch.  

Bottom line.

Vaccines keep your child from having to experience some bad infections.  Vaccines are safe, well researched, and constantly monitored. Get your child vaccinated according to recommendations of the ACIP and your pediatrician.  The only thing you’re doing by waiting is putting your child at risk.   

Links.

Journey of a vaccine.

Herd immunity.

Vaccine education center at CHOP.