Haven’t you “Herd”? The “Herd Mentality” And How Much Control Parents Have In Vaccinating Their Children

Sarah Hines, KLJ Staff Editor[1]

As of February 23, 2015, 154 cases of measles were reported in the United States.[2] This number is significantly greater than the historic national yearly average in recent years.[3] Many of these cases can be tied to a recent outbreak at Disneyland.[4] This recent measles outbreak has sparked much debate among Americans about mandatory vaccination. Some argue that vaccinating as many people as possible will prevent future outbreaks of preventable diseases, such as measles. Others argue that it is every parent’s right to control health care decisions for their children, including whether or not to vaccinate their children.

Not only is measles highly contagious, but it can also cause severe complications such as pneumonia and encephalitis, which can ultimately lead to death.[5] The good news is that a vaccine exists which protects against measles.[6] In Jacobson v. Massachusetts, the Supreme Court upheld a state mandate which required vaccination against smallpox.[7] Many states, including Kentucky, created state laws to mirror this holding and such laws mandate vaccination against certain preventable diseases, including measles.[8] Proof of vaccination is often required for enrolling children into public school systems.[9]

Exceptions do exist in every state for those individuals who cannot be vaccinated for medical reasons.[10] Many states also let parents opt out of vaccinating their children for religious reasons.[11]  Nineteen states allow parents to opt out of vaccinating their children for secular reasons of philosophy or philosophical beliefs.[12] It is this particular opt out policy for “personal beliefs” that is the source of debate.

A small, but noticeable, group of parents opt out of vaccinating their children for personal reasons. These opponents of mandatory vaccination often pin their skepticism of vaccines on the purported safety of the vaccination.  For instance, many believe there is a link between vaccines and autism.[13] Others fear that vaccines can cause digestive health problems or brain damage.[14] Whatever the reason may be for avoiding certain vaccines, some argue that it is a parent’s right to decide whether to vaccinate their own child. As of 2014, thousands of kindergarten-aged children had not been vaccinated.[15]

In opposition to these concerns is a concept called “herd mentality,” the driving force behind laws that require vaccination.[16] The idea is that if most of the people in any given population are vaccinated, then these vaccinated people will act as a barrier against those who cannot be immunized against a certain disease. Those who cannot be immunized will arguably not come into contact with the disease at all, thus slowing or even stopping the spread of certain diseases.

Ultimately, the issue of mandatory vaccination comes down to an issue of public policy. The states are allowed to mandate vaccinations against certain preventable diseases.[17] Similarly, states can carve out any number of personal exceptions to allow parents to opt out of vaccinating their children. The more opt-outs that occur, the less effective the “herd mentality” argument becomes. It is important for states to weigh the risk of disease against the interests of parents who do not want to vaccinate their children. Many states, such as California, are considering legislation to end the “personal belief” exemption to vaccination.[18] Only time will tell how state laws will react to the current measles outbreak and its impact on the issue of parental control of health care decisions for their children.


[1] University Of Kentucky College of Law, J.D. expected May 2016.

[2] Centers for Disease Control and Prevention, Measles Cases and Outbreaks (last updated Feb. 23, 2015), http://www.cdc.gov/measles/cases-outbreaks.html.

[3] Id.

[4] Jonathan Corum, Josh Keller, Haeyoun Park & Archie Tse, Facts About the Measles Outbreak (last updated Feb. 6, 2015), http://www.nytimes.com/interactive/2015/02/02/us/measles-facts.html?_r=0.

[5] Centers for Disease Control and Prevention, Complications of Measles (last updated Feb. 23, 2015), http://www.cdc.gov/measles/about/complications.html.

[6] Id.

[7] Jacobson v. Commonwealth of Massachusetts, 197 U.S. 11, 858 (1905).

[8] E.g., KRS § 214.034.

[9] Id.

[10] Tom Frieden, Stop the Vaccination Debate, Newark Advocate (Feb. 23, 2015), http://www.newarkadvocate.com/story/opinion/columnists/2015/02/23/stop-vaccination-debate/23876185/.

[11] Jacob Gershman, Should Vaccination Be a Choice? In Many States, It Already Is, The Wall Street Journal L. Blog (Feb. 3, 2015), http://blogs.wsj.com/law/2015/02/03/should-vaccination-be-a-choice-in-many-states-it-already-is/.

[12] National Conference of State Legislatures, States With Religious and Philosophical Exemptions From School Immunization Requirements (last updated Feb. 23, 2015), http://www.ncsl.org/research/health/school-immunization-exemption-state-laws.aspx.

[13] The Associated Press, Anti-vaccination parents explain their perspectives: ‘We are not anti-science’ (Feb. 23, 2015), http://www.oregonlive.com/health/index.ssf/2015/02/anti-vaccination_parents_expla.html#.

[14] Id.

[15] Ranee Seither, Svetlana Masalovich, Cynthia L. Knighton, Jenelle Mellerson, James A. Singleton & Stacie M. Greby, Vaccination Coverage Among Children in Kindergarten — United States, 2013–14 School Year (Oct. 17, 2014), http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6341a1.htm.

[16] Sarah Arnquist, Herd Immunity — Vaccinations Protect Us All, The Health Care Blog (July 29, 2008), http://thehealthcareblog.com/blog/2008/07/29/herd-immunity-vaccinations-protect-us-all/.

[17] Jacobson, 197 U.S. at 858.

[18] See, e.g., Jenny Gold, Measles Outbreak Sparks Bid To Strengthen California Vaccine Law (Feb. 5, 2015), http://www.npr.org/blogs/health/2015/02/05/383988632/vaccination-exemption-blamed-for-measles-spread-in-california.