Herd immunity

According to the Centers for Disease Control (CDC), herd immunity (also known as community immunity) is a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely. Even individuals not vaccinated (such as newborns and those with chronic illnesses) are offered some protection because the disease has little opportunity to spread within the community.  The level of vaccination required to achieve herd immunity varies by disease but ranges from 83-94 percent.  When enough people are vaccinated, the infection can’t travel as easily from person to person, and the entire community is less likely to get the disease.  Herd immunity protects everyone, which is why we, joining with our medical colleagues, recommend vaccination.  The U.S. Department of Health and Human Services website (vaccines.gov) even leads with the probing question, ”Did you know that when you get vaccinated, you’re protecting yourself and your community?”

As an ADA Consumer Advisor, I recently had the privilege of representing our profession providing the dentist’s perspective for an Associated Press story headlined Experts Question Benefits of Fluoride-Free Toothpaste.  I spoke with the reporter and reinforced the ADA’s position that brushing with fluoride toothpaste is necessary to prevent cavities. The story has been featured in over 644 print and broadcast media outlets, including “The New York Times” and ABCnews.com, leading to more than 824 million impressions. The “Today Show,” which is watched by more than 4 million people each day, also did a segment following the AP story and I was able to thoroughly brief the “Today Show” producer prior to their coverage.  ADA Communications shared an image depicting age-appropriate amounts of fluoride toothpaste, which was used in the segment and credited to the ADA.  Our recommendation is for “The Healthy 4” – brush twice a day with a fluoride toothpaste, clean between your teeth (floss) once a day, eat a healthy diet and see your dentist on a regular basis.  Our statements are respected because I tell reporters that I represent the 161,000 members of the American Dental Association.

Professor David Rehr of George Mason University recently surveyed congressional staff concerning their impression of organizations advocating for policy on Capitol Hill.  They compared the ADA with organizations such as the American Medical Association (AMA), the Pew Charitable Trusts, Delta Dental, and the American Association of Retired Persons (AARP) among others.  The ADA ranked extremely highly in all categories, including in credibility (No. 2 behind only Pew and ahead of AARP!), effectiveness, favorability (higher than AMA) and visibility.  We have built the relationships to hang with the big dogs like AARP.  The ADA has clout on Capitol Hill, and in statehouses around the country, because we represent nearly 70 percent of all dentists, where the AMA now has a membership of less than 25 percent of physicians.  The ADA has credibility because we have a reputation for building relationships with members of all sides of the political spectrum.  As we tell both Republicans and Democrats, we are the Tooth Party. 

When I talk with dentists, both young and more seasoned, they tell me that the things they value most from the profession are advocacy and representation.  From a membership perspective, these attributes come whether someone is a member or not.  All dentists benefit from the ADA’s efforts in communications.  We are the source for evidenced-based recommendations to the public.  Our patients place a high value on the ADA Seal of Acceptance and look to us for guidance in answering their questions on oral health.  All dentists benefit from the ADA’s tireless efforts on Capitol Hill and in state legislatures around the country.  We advocate for patients who can’t speak for themselves and provide one voice for the profession. The ADA is the only professional dental organization that bridges the power of the public and the practice of dentistry.  It is something that we have traditionally done well and we should be rightly proud.

However, nothing is immune to change.  Herd immunity is known to be vulnerable to what is called the “free rider” problem.  Individuals who lack immunity, primarily those who choose not to vaccinate, “free ride” off the herd immunity created by those who are immune.  As the number of free riders in the population increases, outbreaks of preventable diseases become more common and more severe due to the loss of herd immunity.  Individuals are more likely to “free ride” if vaccination rates are high enough so as to convince a person that they may not need to be immune since a sufficient number of others already are. 

Membership in the American Dental Association has traditionally been exceptionally high, due to the exemplary commitment to the profession shown by our predecessors.  This has provided a high level of herd immunity to us all.  When we are all members, we have the ability to inoculate the profession against a number of outside forces.  As membership percentages decline, we risk losing our ability to speak forcefully for the profession. 

Yes, all dentists benefit from the ADA – whether they are members or not. But we have a personal obligation to the profession of dentistry, the community of dentists, and our patients to stay strong.  An ADA speaking with one voice, united, represents the best hope our patients have for their oral health.  Did you know that when you become a member, you are protecting yourself and your community?

Dr. Messina may be reached at docmessina87@gmail.com.