Every year in the United States, vaccination against 13 key diseases during early childhood is estimated to prevent 20 million cases of disease, save 40,000 lives, and add $69 billion in economic benefits to U.S. society.  By countless measures, the development and implementation of childhood vaccinations over the past eighty years has been an enormous success that has improved life outcomes for millions of children.

But recently, the childhood vaccination rate has been falling as more and more parents are choosing to not vaccinate their children.  Since 2001, the number of children under two years of age who have not received any vaccines has quadrupled from 0.3 percent to 1.3 percent.  While this may still seem like a very small percentage, this growing minority had already led to increased rates of diseases that are fully preventable with vaccines.  

Let’s take the example of measles.  In 2000, measles was officially declared eliminated in the U.S.  This was largely due to widespread vaccine coverage in children.  However, two decades later, the scene has changed.  Between January and September of 2019, 1,249 cases of measles were reported in the U.S., the highest number in that timespan since 1992. Of the people who contracted measles, only 11% were confirmed to have been vaccinated.

Like most issues in the world, the current decrease in childhood vaccination does not have a single cause.  Lack of firsthand experience with the diseases vaccines prevent, inaccurate information about the safety of vaccination, and public statements against vaccination by well-known individuals have all played a part in influencing parents to not vaccinate their children.  However, one significant source of falling vaccination rates that is often under-estimated is the role of fear-inducing information online.  

A 2018 study shows that 90% of parents in the U.S. use the Internet to search for health-related information about their children.  However, the study also found that the majority of these parents are unsure whether the information they find is trustworthy or not. This is dangerous because many commonly-used areas of the Internet, such as social media sites, do not select what information is posted or favored based on its accuracy.  Posts that elicit strong emotions are the ones more likely to be shared, and posts that elicit strong negative emotions are the most shared of all.

Social media algorithms therefore would favor an emotional post about a child who got sick after a vaccine far more than it would a scientific post about the benefits of vaccination.  Over time, each emotional post, even if inaccurate, spreads to many people and drives public opinion of vaccines far more than less emotional, but accurate, scientific posts.  

For example, consider this Facebook ad:

This ad plays with the emotions of an observer in multiple ways.  It first attracts your attention with a picture of an adorable baby right next to the large text “Vaccines Kill Babies.”  It includes the emotional story of a mom following her child to the hospital and finding out that it was too late and he has died from a scary-sounding disease.  This would elicit an emotional reaction of fear in any parent concerned about keeping their young child healthy.  

If even a fraction of the parents who see ads such as these decide to not vaccinate their children, the public health impact could be severe.  Vaccines only protect people against disease when almost all members of a population are vaccinated and the population reaches what is termed “herd immunity.” Herd immunity is a precarious state, however, and the drop of a few percentage points in vaccination coverage is often the determining factor between no epidemic and an epidemic.

Choosing to vaccinate your child, therefore, helps everyone, while choosing not to vaccinate puts the entire population at risk of disease, even those who are vaccinated.  

Pressuring social media companies to prevent vaccination misinformation should be a public health priority.  Posts with content or hashtags containing vaccination misinformation can be blocked, misleading advertisements can be banned, and pop ups that direct viewers to reputable health websites can appear before any vaccine-related content, so that users see credible information first.  While these proposed steps will not prevent every parent from believing the emotional information they come across against vaccination, they can maybe prevent some.  And with vaccination, a few people’s actions can make a big difference.  

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References: 

Burki, Talha. “Vaccine Misinformation and Social Media.” The Lancet Digital Health 1, no. 6 (October 2019): e258–59. https://doi.org/10.1016/S2589-7500(19)30136-0.

Hill, Holly A. “Vaccination Coverage among Children Aged 19–35 Months — United States, 2017.” MMWR. Morbidity and Mortality Weekly Report 67 (October 12, 2018). https://doi.org/10.15585/mmwr.mm6740a4.

Offit, Paul. “Vaccine History: Developments by Year.” Text. Children’s Hospital of Philadephia, November 20, 2014. https://www.chop.edu/centers-programs/vaccine-education-center/vaccine-history/developments-by-year.

Orenstein, Walter A., and Rafi Ahmed. “Simply Put: Vaccination Saves Lives.” Proceedings of the National Academy of Sciences of the United States of America 114, no. 16 (April 18, 2017): 4031–33. https://doi.org/10.1073/pnas.1704507114.

Patel, Manisha. “National Update on Measles Cases and Outbreaks — United States, January 1–October 1, 2019.” MMWR. Morbidity and Mortality Weekly Report 68 (2019). https://doi.org/10.15585/mmwr.mm6840e2.

Sivek, Susan Currie1. “Both Facts and Feelings: Emotion and News Literacy.” Journal of Media Literacy Education 10, no. 2 (May 2018): 123–38. https://doi.org/10.23860/JMLE-2018-10-2-7.

Sun, Lena H. “Percentage of Young U.S. Children Who Don’t Receive Any Vaccines Has Quadrupled since 2001.” Washington Post, October 11, 2018, sec. Health & Science. https://www.washingtonpost.com/national/health-science/percentage-of-young-us-children-who-dont-receive-any-vaccines-has-quadrupled-since-2001/2018/10/11/4a9cca98-cd0d-11e8-920f-dd52e1ae4570_story.html.

Wong, Julia Carrie. “How Facebook and YouTube Help Spread Anti-Vaxxer Propaganda.” The Guardian, February 1, 2019, sec. Media. https://www.theguardian.com/media/2019/feb/01/facebook-youtube-anti-vaccination-misinformation-social-media.

Yardi, Shruti, Patrina HY Caldwell, Elizabeth H. Barnes, and Karen M. Scott. “Determining Parents’ Patterns of Behaviour When Searching for Online Information on Their Child’s Health.” Journal of Paediatrics and Child Health 54, no. 11 (2018): 1246–54. https://doi.org/10.1111/jpc.14068.