COMMENTARIES Editorials represent the opinions of the authors and not necessarily those of the American Dental Association. EDITORIAL Vaccine hesitancy and unfalsifiability ’ ’ Michael Glick, DMD Editor s note: In this issue s new A Safer Dental Visit feature published in collaboration with OSAP, The Safest Dental Visit titled “Managing Measles in Dental Practice: A Forgotten Foe Makes a Comeback,” on page 558, Sara C. Gordon, DDS, MSc, FRCD(C), FDS-RCS(Edin), and Noni E. MacDonald, MD, MSc, FRCP(C), discuss what dentists can do to ensure that the risk of measles transmission is as low as possible in their dental offices. uch has been said, debated, and written about the purported association between the measles, mumps, and rubella (MMR) vaccine and the development of autism. The initial report by M 1 1998 Wakefield and colleagues in , claiming the MMR vaccine caused autistic behavior, resulted in a rise in vaccine hesitancy (varying degree of acceptance) to outright refusal of state-recommended childhood immunization schedules and a subsequent decline in the number of immunized children. Geographical clusters of endemic measles and pertussis, or whooping cough, outbreaks ensued in areas with a high prevalence of parents or 2 3 guardians who refused to have their children vaccinated. , Wakefield and 1 colleagues’ article eventually was retracted because it was deemed scien- tifically and ethically flawed because of deliberate fraudulent conduct, 4 5 and Andrew J. Wakefield’s, MB, medical license later was revoked. , In- vestigators in several subsequent studies have not been able to show any 6 7 association between the MMR vaccine and autism. , However, despite scientific evidence to the contrary, vaccine hesitancy persists. There are excellent reviews in which the authors discuss reasons for this worrisome 8 9 trend. , Reasons include social media and Internet influences, knowledge and attitudes, distrust in health systems, disapproval of governmental oversight—but probably most important, the inability to separate evidence from emotive anecdotes. All states, except Mississippi and West Virginia, allow religious and philosophical vaccination exemptions, and 19 states allow exemptions solely 10 based on philosophical or personal beliefs. Temporary or permanent medical exemptions are permitted in all states and include exemptions for children with immunodeficiencies, children with allergies to the vaccine or its components, or children who already have developed natural immunity. State requirements for immunization are linked to a child’s entry into the school system. Interestingly, significant differences are evident when comparing exemption rates between private and public schools. JADA 146(7) http://jada.ada.org July 2015 491 COMMENTARIES Results from a study in 2014 communities with low immunization create a fictional scientific rationale. showed more than double the overall rates. An unfortunate consequence It is easier to believe that a vaccine exemption rate in private schools of increased numbers of unvacci- caused autism than to accept that we than in public schools (4.25% versus nated people in specific or clustered may not have an explanation for the 1.91%), with similar differences noted communities is the decline in herd cause of this condition. for medical (0.58% versus 0.34%), immunity. As oral health care professionals, religious (2.09% versus 0.83%), and Herd immunity usually refers to we treat oral diseases, but we also personal belief (6.10% versus 2.79%) maintaining a minimal proportion of are considered respected and trusted 11 exemptions. These data correlate immune people to susceptible people resources in our communities on with those of other studies in which to minimize periodic epidemic out- broader health issues. Although the investigators characterized in- breaks of vaccine-preventable dis- almost three-quarters of parents 15 fants who did not receive routine eases. When the prevalence of trust vaccine safety information vaccination as being more likely to vaccinated or immune people falls provided to them by their children’s be male, be white, have 4 or more below a certain threshold, epidemics pediatrician, only one-quarter of siblings, and live in households with may arise. The vaccination rate to parents have confidence in the same married parents who are college achieve herd immunity for measles type of information when provided 16 18 educated and have an annual income may be in excess of 95%. by other health care professionals. of $75,000 or greater than are It is sometimes amusing to hear Interestingly, the same level of 12 vaccinated children. how celebrities are asked about their trust given to nonpediatricians, one- Observed rising incidence rates of views on biomedical topics, such quarter, also is awarded to celeb- some vaccine-preventable diseases, as alternate cancer therapies or im- rities. Collecting immunization data such as pertussis, can be explained munization. The amusing part is from all patients provides the op- by disease-reporting bias and the to wonder why we would assume portunity to initiate a conversation lack of lifelong, or waning, immunity that a movie actor would be versed with parents who may be vaccine from natural infections and vac- in scientific facts, reasoning, and hesitant about the risks and benefits 2 cines. Increased awareness of the thinking—and why we actually of vaccination. Regrettably, chal- disease may result in more reported would care about what the actor lenging the belief systems of staunch cases, and, unfortunately, reduced thinks about scientific issues. This supporters of absolute vaccination vaccine effectiveness and duration of does not mean he or she does not refusal may not be successful and protection with the now more possess the necessary capabilities to actually may strengthen their commonly used acellular pertussis attain scientific knowledge and argue resolve. vaccine than with whole-cell vaccine science matters. It only means that I do not know the reason for have contributed to more cases of he or she may not have the knowl- autism or other conditions blamed 13 pertussis. edge necessary to understand what on immunization, but I do know that The increased incidence of mea- the latest scientific findings might be. lack of immunization may result in sles may be due to other causes. The Mostly, nonscientists latch on to a the reemergence of diseases that introduction of an effective vaccine certain view, not realizing that, at we thought we had conquered. in 1963 resulted in measles being least among biomedical sciences, Becoming a knowledgeable resource declared eliminated in the United dramatic changes occur over short on health issues that affect our States in 2000, yet a dramatic resur- time spans. The not-so-amusing part communities, such as the benefits 14 gence of cases now is being reported. is how some celebrities, politicians, and harms of vaccination, will go a In 2014, the Centers for Disease and other nonmedically trained long way toward allaying the fear of Control and Prevention documented people are given great media expo- the unknown and increase the almost 650 new cases, and from sure even when their views and already high respect we have earned January 1, 2015, to April 24, 2015, 166 beliefs may result in harm. from our patients. n cases from 19 different states have The problem with belief systems 3 10 1016 2015 05 003 been reported already. Many of the is that they include elements of http://dx.doi.org/ . /j.adaj. outbreaks emanate from imported unfalsifiability—elements that ª 17 Copyright 2015 American Dental cases in which infected travelers cannot be tested and proved false. Association. All rights reserved. from other countries in the world Unfortunately, many of us crave an fi Dr. Glick is the dean, School of Dental Medi- brought the disease to the United explanation or justi cation for why cine, University at Buffalo, The State University States. bad things happen. When solid of New York, Buffalo, NY. He also is the editor of However, the intentional delay or scientific rationales or evidence are The Journal of the American Dental Association. refusal to vaccinate children because not available, we often blame unex- Address correspondence to Dr. Glick at School of Dental Medicine, University at Buffalo, The State of ideological beliefs promulgates the plainable health outcomes on University of New York, 325 Squire Hall, Buffalo, spread of this disease, particularly in perceived nefarious reasons, or we NY 14214-8006, e-mail [email protected]. 492 JADA 146(7) http://jada.ada.org July 2015 COMMENTARIES Disclosure. Dr. Glick did not report any and cohort studies. Vaccine. 2014;32(29): 13. Gambhir M, Clark TA, Cauchemez S, disclosures. 3623-3629. Tartof SY, Swerdlow DL, Ferguson NM. 7. Jain A, Marshall J, Buikema A, Bancroft T, A change in vaccine efficacy and duration of 1. Wakefield AJ, Murch SH, Anthony A, Kelly JP, Newschaffer CJ. Autism occurrence by protection explains recent rises in pertussis et al. Ileal-lymphoid-nodular hyperplasia, MMR vaccine among US children with older incidence in the United States. PLoS Comput non-specific colitis, and pervasive develop- siblings with and without autism. JAMA. 2015; Biol. 2015;11(4):e1004138. mental disorder in children [retracted in: 313(15):1534-1540. 14. Centers for Disease Control and Preven- Lancet. 2010;375(9713):445]. Lancet. 1998; 8. Dubé E, Vivion M, MacDonald NE. tion. Measles history. Available at: http://www. 351(9103):637-641. Vaccine hesitancy, vaccine refusal and the anti- cdc.gov/measles/about/history.html. Accessed 2. Cherry JD. Epidemic pertussis in 2012: the vaccine movement: influence, impact and im- June 1, 2015. resurgence of a vaccine-preventable disease. plications. Expert Rev Vaccines. 2015;14(1):99-117. 15. Fine P, Eames K, Heyman DL. “Herd im- N Engl J Med. 2012;367(9):785-787. 9. Siddiqui M, Salmon DA, Omer SB. Epide- munity”: a rough guide. Clin Infect Dis. 2011; 3.