Common Vaccination Questions

As a board certified general pediatrician working in an outpatient clinic, vaccine conversations are a routine part of my day. Vaccine hesitancy is common, and outright vaccine refusal rates are rising in my community. Parents are now routinely exposed to anti-vaccine propaganda, so providers who are administering vaccines in 2019 must be aware of the most common concerns and be prepared to address them confidently. Vaccine discussions are often stretched over a series of visits and building trust with families is paramount to overcoming misinformation. Aside from having appropriate patient education handy to share with my parents in advance of and during visits, I have compiled common questions and their answers to be readily able to respond to inquiries.  What follows are the most common questions I’m fielding lately and my responses.

Which vaccines contain thimerosalThimerosal is a vaccine preservative that contains ethlymercury and is found only in multi-dose preparations of the influenza vaccine. There are no childhood immunizations that contain thimerosal—it was removed entirely by the year 2000. Ethylmercury is often mistaken for its more dangerous cousin, methylmercury, which in high concentrations can be dangerous to humans. In fact, ethylmercury is broken down and excreted by the body much faster than methylmercury, but with the removal of thimerosal this is a non-issue.

Why should I vaccinate against something if it’s not required for school? This is a reasonable question that comes up when discussing several vaccines, including those for hepatitis A, HPV, and certain strains of meningitis. My answer is simply that medical best practice does not always perfectly align with the requirements of the public schoolsystem in the United States. Physicians and scientists at the CDC and the ACIP who understand the relevant risks to our patients create the vaccine schedule, which is then vetted by the AAP and the American Academy of Family Practitioners before making a recommendation. A recommendation to vaccinate according to the CDC vaccination schedule should carry more weight than a mandate by the school system.

Can I separate out the MMRvaccine? Separate components for the m-m-r are no longer recommended or manufactured in the United States. The combination vaccine is safe and effective, and there is no evidence that splitting it up is beneficial. The MMR vaccine is given in two doses, the first is after 12 months of age and the second between age 4 and 6 years of age.

Do vaccines cause autism, diabetes, food allergies, or seizure disorders?
The suggestion that vaccines cause autism has been disproven over and over and around the globe. Nevertheless, this conversation involves compassionate listening to be effective. Caregivers want to avoid harm to their child, which is understandable. I have found it’s best to completely hear out a family’s concerns in order to respond clearly and with empathy.

Can I wait until my baby is a bit older to vaccinate? This question arises more commonly with families who have a caregiver staying home with their child, since day care centers are required to follow the mandated vaccine schedule set by each state. While we cannot force anyone to vaccinate according to the recommended vaccine schedule, timing of the vaccines is outlined precisely because infants are particularly vulnerable to the diseases in question. The vaccines are given in infancy when the immune system is not mature enough to mount a sophisticated response to the disease if acquired naturally. Multiple doses are necessary to create a mature immunity to the disease.

What are the risks of vaccines? When parents ask about risks, I assume what they are asking is if the risks of the disease are higher than the risk of the vaccine itself. As vaccine-preventable diseases fade from society’s collective memory, rare vaccine side effects (such as the 1-in-1,000,000 risk of anaphylaxis) can seem high. Measles outbreaks are reminding people to a certain extent that the risk of illness far outweighs the risk of disease, but we are largely spoiled by the overwhelming success of the U.S.’s high vaccination rate. In addition, due to herd immunity, even unvaccinated people feel safe from these terrible diseases. Here it can be helpful to use personal examples to help families understand that we are only a couple generations away from when many Americans suffered catastrophic consequences of polio (paralysis), whooping cough (my grandmother lost sight in one eye due to a retinal detachment caused by a coughing paroxysm), HIB meningitis (deafness) and measles (encephalitis).


  1. Centers for Disease Control and Prevention. Vaccination Coverage for Selected Vaccines and Exemption Rates Among Children in Kindergarten.
  2. Centers for Disease Control and Prevention. Q&A About Monovalent M-M-R Vaccines.
  3. Families Fighting Flu.
  4. Immunization Action Coalition.
  5. McNeil MM, Weintraub ES, Duffy J, Sukumaran L, Jacobsen SJ, Klein NP, Hambidge SJ, Lee GM, Jackson LA, Irving SA, King JP, Kharbanda EO, Bednarczyk RA, DeStefano F. Risk of anaphylaxis after vaccination in children and adults. J Allergy Clin Immunol. 2016 Mar;137(3):868-78.