Because August is National Immunization Awareness month, I thought I’d address vaccines. Parents are savvy and ask great questions. Vaccine concerns are no exception. I spend a huge part of my work day discussing vaccines. These are the most common questions I get.

1. Are vaccines safe?

The short answer is: yes. The longer answer is that to be completely honest, there is some risk with all vaccines. In short, the benefits outweigh the risk. In all cases, the risks from the disease are far greater than the risk from the vaccine. Just like one would say that walking on the sidewalk is “safe,” but you could fall and get hurt or a car could come careening around the corner and hit you. However, most would agree that walking on the sidewalk (getting the vaccine) is safer than walking in the middle of the street (the risk of getting the disease). To get approved for use, vaccines go through an extensive process of study, trials, and reviews before getting the seal of approval from the Food and Drug Administration (FDA). Additionally, all vaccines go through a review process by the Centers for Disease Control and Prevention (CDC), American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP). Interestingly enough, vaccines continue to be monitored for any side effects or problems that may arise after going to market (using a program called the VAERS [Vaccine Adverse Event Reporting System]).

2. What are the side effects?

The most common side effects from most of the vaccines are fever, irritability, and pain or redness at the site of injection. For many of the shots, the most serious side effect is the potential for a severe allergic reaction or anaphylaxis. This reaction happens about at a rate of 1 in a million. Each individual vaccine will have other listed potential risks, e.g., the HPV has a higher risk of fainting and headache with the shot, the MMR has a risk of febrile seizures (1 in 3,000 according to the CDC).  I’m a parent, I get the concern. I don’t want my child to be the one in a million. However, I’m also good at math and understand that the risk of the disease (in some cases as low as 1 in a few hundred) is much worse. I figure that if I’m going to have to gamble, I’ll side with the house. The odds are better.

3. Is it too many vaccines at one time?

This question is really getting at the concern of whether all the different vaccines are too much for an infant’s immune system. 100 years ago, kids routinely got 1 vaccine (small pox), 40 years ago, kids routinely got 5 vaccines (8 total in the series by age 2), now kids routinely get 11 vaccines (20 total in the series by age 2). This is a significant increase. No wonder parents are concerned. The good news is that while the number of vaccines have increased, the amount of antigen (the actual little components of bacteria or viruses that cause disease) has decreased significantly over time. Scientists have realized that the body can develop an immune response with far fewer antigens. So you’re getting more coverage with less of an antigen exposure. You’re actually getting more for less.

4. Can I limit the number of pokes my child gets?

Yes. Here’s the great news. Many of the vaccines come in combinations and many pediatricians’ offices are stocking these combination vaccinations. Examples are  Pediarix (DtaP, Hep B, IPV), Pentacel (DtaP, Hib, IPV), Kinrix (DtaP and IPV), and Proquad (MMR and Varicella) to name a few. Combination vaccines usually put 2 or 3 shots into one. However, be advised that the shots have to be manufactured that way (where they were FDA-studied and approved for safety and efficacy). Your doctor cannot just mix shots together in the same vial.

5. Do vaccines have thimerosal?

Thimerosal was used as a preservative in vaccines for many years. The concern around thimerosal stems from the fact that it contains 49.6% mercury (which is bad for your brain). As a consequence, the FDA Modernization Act of 1997 resulted in the removal of thimerosal from standard childhood immunizations by 2001 (the one exception in the standard vaccines is the multi-dose injectable/killed flu vaccine).

6. If everyone else is vaccinated, why should I? Isn’t my child protected?

This phenomena is called “herd immunity.” The way it works is that once a population or group reaches a critical percentage of people vaccinated (often greater than 90-95%) everyone gets some protection from the disease (even those too young or sick to be vaccinated) by factor of decreasing the disease burden because the disease doesn’t spread around a vaccinated population. The problem with this theory is that too many parents have relied on this plan, which has caused the vaccination levels to drop below the critical threshold. This is why we are regularly seeing outbreaks across the nation of vaccine-preventable diseases. Examples this year (2017) include 1.4 million cases of measles (with outbreaks in 12 states), 42,000 cases of mumps (with outbreaks in 20 states), and 128,000 cases of whooping cough (with outbreaks in 9 states) to name just a few. (All numbers were obtained from the council of foreign relations map of vaccine preventable outbreaks).

7. Do vaccines cause autism?

The concern over vaccines (specifically the MMR) causing autism originated from a 1998 study published by Dr. Andrew Wakefield in The Lancet. Since then, the paper was completely discredited (due to procedural errors, undisclosed financial conflicts of interest, and ethical violations), the paper was retracted, and the doctor lost his license. However, the damage was done. Despite multiple scientific studies disproving the connection, the worry persists. While autism is not fully understood by the medical community, most agree that it has a multifactorial cause with some genetic and some environmental links.

8. Why does my child have to get multiple doses of the same vaccine?

Some vaccines give a low level of protection after a single dose, but as more doses are given, the immune response improves.  The DtaP (pertussis, tetanus, and diphtheria) vaccine is a great example of this. While you can give multiple vaccines at the same time (as mentioned in question number 3), with some vaccines, you simply can’t give all the protection against that individual vaccine all in one dose. The immunity to that particular disease is built a step at a time. I think of it like sunscreen. If your child is going to be outside all day, slathering sunscreen on really thick just once at the beginning of the day, probably won’t be enough.

Other vaccines are given to increase the number of people who respond or develop immunity to the vaccine (a subtle difference from the first reason). For example, 78% of adults who get the chicken pox shot will develop immunity after one dose, but you increase the number to 99% by giving a second shot. Since the additional dose isn’t harmful, it’s worth the extra shot to catch 21% more people.

9. Does that disease even exist in the United States?

It doesn’t matter what that disease is, the short answer is yes. Since we are a global world, no one is immune. Every disease is only one airplane ride away. Take polio for example. The United States hasn’t had any reported cases this year (to my knowledge). However, there have been 2,686 reported cases in 4 different countries (again according to the council on foreign relations) this year alone. Is the risk high? Probably not, especially compared to 1.4 million cases of measles, but why even take the chance when it is completely preventable?

10. My child isn’t sexually active, does he/she really need HPV or Hepatitis B?

Yes, yes, yes. First, there is more than one way to get some diseases. Take Hepatitis B for example, a child can get it from the mother (direct transmission to the fetus) or a miniscule amount of blood exposure (e.g., sharing a tooth brush with an infected person and having a small sore in the mouth). It doesn’t have to be the traditional IV drug user or sexual exposure. Second, there isn’t a cure for these diseases, only prevention. Once your child (even if he/she is 40 when it happens) has cervical cancer from HPV or liver failure from Hep B, it’s too late, the damage is done. Third, the immune system mounts a hardy response to these vaccines at this young age (the recommendation for ages of administration are such because the vaccines have been studied to have the best response at those ages). Fourth, protect against the unthinkable exposure. (Heaven forbid your child get sexually violated by an infected person or is sexually active without your knowledge.) Why not put up every possible defense to protect your child? Lastly, the vaccines are expensive. Do it while vaccines for your child are covered 100% either under your insurance or the Vaccines for Children, VFC program. If your child is 25, uninsured, and working with a limited budget, I can almost guarantee he/she won’t choose to pay for vaccines then.


I hope this helps answer some of the common questions and concerns. As you decide what is best for you and your child, keep the facts in mind. The 999,999 who didn’t have a problem with the vaccine and didn’t get the disease don’t blog the good news, “Yeah, my child didn’t get pertussis, measles, or varicella encephalitis.” They just go about their healthy, disease-free lives. Inevitably, you read about the 1 who had the rare side effect, leading you to believe it is more common than it is.

It’s amazing to me how many times I get asked the question, “What would you do?” when parents are uncertain about a medical decision. Sometimes that can be hard to answer. In the case of vaccines, it was an easy choice for me. I’ve had the perspective of taking care of kids suffering from vaccine preventable diseases. I vaccinated all my children, according to the recommended schedule. And I would do it again in a heartbeat.

Good luck!

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About The Author

Dr. Monica Wonnacott

I'm a pediatrician and a mom. I've been doing this doctor thing for 10 years, and love it. I'm known for giving parents the straight scoop without always sugar-coating it. And I believe in educating parents. The more you know, the better care you give your kids.

Dr. Monica Wonnacott

I'm a pediatrician and a mom. is my blog where parents can get the straight scoop on their child's health, largely based on my experience in the office and at home. I don't diagnose on the site, so please don't ask. These are just my opinions. Use this site as a resource. And trust your parent gut.

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