As the recent Disneyland-associated measles outbreak demonstrates, children who are unvaccinated — often due to parental fears — are a major source of the spread of vaccine-preventable disease.

Parents who choose not to vaccinate their children may not appreciate that measles is a serious disease and can cause pneumonia, encephalitis, or even death. For health care providers, parental resistance to vaccination can be frustrating, particularly when it is based on misunderstanding of the enormous benefits of vaccination. What is the best way to explain the vital importance of childhood vaccination?


Parents today are bombarded with information about vaccination. Some of it is sound, but much of it is not, and it can be difficult for parents to tell the difference. So it is understandable that they have questions about safety and effectiveness.

Research shows that parents are more likely to vaccinate their children if they have a strong relationship with and trust their child’s health care provider (Public Health Rep. 2011;126[suppl 2]:135-146). Therefore, it is important to listen to parents’ questions and concerns with a sympathetic ear, understand their fears, and carefully explain that the science is crystal clear—immunization is one of the most important things we can do to protect ourselves against serious diseases.

The CDC estimates that among children born between 1994 and 2013, vaccination will prevent about 322 million illnesses, 21 million hospitalizations, and 732,000 deaths during their lifetimes.


Children are far more likely to be harmed by measles (and other vaccine-preventable diseases) than by the vaccine, and the FDA tests each new vaccine for as long as 10 years before approving it. Some children may have a reaction, but most are minor, such as fever or soreness. Severe reactions are rare. Parents should be alerted to the vaccine safety portion of the CDC’s website, which provides extensive information to address their concerns. 


Measles, which is highly contagious and the most deadly of the rash/fever childhood illnesses, killed more children younger than age 5 worldwide than car accidents or HIV infection in 2013 (Lancet. 2015;385:117-171). Two doses of the MMR vaccine will prevent 97% of recipients from getting measles.

Without the vaccine, 90% of those exposed to measles will become infected. Most childhood vaccines are about 90% effective if the full number of doses is received: the DTaP vaccine is given early in life because pertussis is potentially fatal for infants (although a booster is necessary during adolescence to ensure continued protection); chicken pox is highly contagious and potentially deadly; and rotavirus can cause severe dehydration and death.


Explaining to parents that vaccinating their children helps protect those who cannot be vaccinated—from the infant in daycare who is too young to be immunized, to the friend undergoing chemotherapy, to the pregnant neighbor and her unborn child. All of these reasons are why health groups such as the Infectious Diseases Society of America and its members firmly believe in universal immunization of children, adolescents, and adults according to the recommendations and standards established by the CDC. 


Vaccines are effective in saving lives, and concerns about their safety are often based on misinformation rather than on science. Communicating the benefits of vaccines to skeptical parents can be a challenge, but it is one that we can overcome together.


Stephen B. Calderwood, MD, is Chief, Division of Infectious Diseases, and Vice Chair,
 Department of Medicine, Massachusetts General Hospital; Professor of Medicine,
 Harvard Medical School; and president of the Infectious Diseases Society of America.