By Brennen McKenzie, MA, MSc, VMD, Cvma

In reference to a letter to the editor by Todd Cooney, DVM, CVH, that appeared in the February 2020 issue of Veterinary Practice News, it is disappointing to have to respond to this collection of false claims. The World Health Organization (WHO) has declared vaccine hesitancy one of the top 10 public health threats,¹ and anti-vaccine misinformation such as these claims has led directly to increased suffering and death from vaccine-preventable disease.^2,3 Merely printing this misinformation exemplifies the problem of media false balance, which amplifies extreme anti-science viewpoints and contributes to vaccine hesitancy.^4,5 While it is simple to fact-check Dr. Cooney's statements, it is also clear he and those who share his beliefs are not interested in facts. I offer views expressed in his letter, followed by my response:

• False claim: Infectious disease declined due to sanitation and other public health measures before vaccination was introduced.

Facts: There is consistent evidence that rates of many infectious diseases drop precipitously after introduction of vaccines, regardless of local levels of hygiene and despite the persistence of these diseases for centuries prior to the development of vaccines. This is demonstrable for measles, Haemophilus influenza type B, whooping cough, and many others.^6–8 Such diseases also recur when vaccination rates drop, despite no change in hygienic conditions.^9,10

• False claim: Homeopathic nosodes are more effective than vaccines for canine parvovirus.

Facts: This anecdote is inconsistent with the experiences of most veterinarians. In 20 years of practice, for example, I have never used nosodes and have only seen parvovirus in unvaccinated dogs. More importantly, it is also contradicted by controlled clinical studies, showing no protective effect of nosodes against parvovirus and no immune response at all to nosodes in humans.^11,12 Nosodes do nothing.

• False claim: Vaccines trigger autoimmunity in 100 percent of dogs.

Facts: Extensive research over several decades has failed to find convincing evidence that vaccines are a significant cause of autoimmune disease.¹³ If such diseases are triggered by vaccines in some individuals, this risk is rare and far outweighed by the benefits of vaccination for the vast majority of cats and dogs.

• False claim: The majority of measles and mumps infections occur in vaccinated individuals, so vaccine-induced herd immunity doesn't work.

Facts: Two doses of the MMR vaccine is estimated to be 97 percent effective at preventing measles and 88 percent effective at preventing mumps.¹⁴ The vaccine greatly reduces individual risk of infection, but in highly vaccinated populations, some of the cases will be in vaccinated individuals. In the 2015 California measles outbreak, for example, 96 percent of the population was vaccinated, and roughly 20 percent of cases were in vaccinated individuals.¹⁵ This is not even close to the false figures in Dr. Cooney's letter, and it does not indicate vaccination is ineffective.

• False claim: Herd immunity only works with natural infection, not vaccination.

Facts: Effective herd immunity has been proven to occur with numerous vaccines.¹⁶ Natural immunity requires becoming infected, which entails a far greater risk of harm than any posed by vaccines.

• False claim: Homeopathy was proven effective against Spanish Flu in 1918.

Facts: This is only a story told by homeopaths based on uncontrolled anecdotes from other homeopaths. There is no objective research evidence showing homeopathy as an effective treatment for the flu, not in 1918 and not in any of the many flu outbreaks that have occurred in the hundred years since. There is plenty of research evidence showing homeopathy is ineffective for any disease.¹⁷

Apparently, my "stunning ignorance of the history of communicable diseases" is shared by the Centers for Disease Control and Prevention (CDC), WHO, and every other public health agency in the world, as well as the vast majority of veterinarians and physicians. The "truth," as Dr. Cooney sees it, is recognized only by a handful of believers in the magical nonsense that is homeopathy. What are the odds? It is sad and shameful such anti-vaccine views have misled enough people to bring about the resurgence of vaccine-preventable diseases, and the suffering and death this causes in humans and animals.

References

1. Ten threats to global health in 2019. https://www.who.int/emergencies/ten-threats-to-global-health-in-2019. Accessed January 10, 2020.
2. Phadke VK, Bednarczyk RA, Salmon DA, Omer SB. Association between vaccine refusal and vaccine-preventable diseases in the United States A review of measles and pertussis. JAMA - J Am Med Assoc. 2016;315(11):1149-1158. doi:10.1001/jama.2016.1353
3. Lo NC, Hotez PJ. Public health and economic consequences of vaccine hesitancy for measles in the United States. JAMA Pediatr. 2017;171(9):887-892. doi:10.1001/jamapediatrics.2017.1695
4. Dixon GN, Clarke CE. Heightening Uncertainty Around Certain Science: Media Coverage, False Balance, and the Autism-Vaccine Controversy. Sci Commun. 2013;35(3):358-382. doi:10.1177/1075547012458290
5. Dixon G, Clarke C. The effect of falsely balanced reporting of the autism-vaccine controversy on vaccine safety perceptions and behavioral intentions. Health Educ Res. 2013;28(2):352-359. doi:10.1093/her/cys110
6. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention. Measles, Mumps, and Rubella — Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome and Control of Mumps: Recommendations of the Advisory Committee on Immunization Pract. MMWR. 1998;47(RR-8).
7. Roush SW, Murphy T V., Basket MM, et al. Historical comparisons of morbidity and mortality for vaccine-preventable diseases in the United States. J Am Med Assoc. 2007;298(18):2155-2163. doi:10.1001/jama.298.18.2155
8. World Health Organization (WHO). WHO | Six common misconceptions about immunization. https://www.who.int/vaccine_safety/initiative/detection/immunization_misconceptions/en/index1.html. Accessed January 10, 2020.
9. Hotez P. America and Europe's new normal: the return of vaccine-preventable diseases. Pediatr Res. 2019;85(7):912-914. doi:10.1038/s41390-019-0354-3
10. Paules CI, Marston HD, Fauci AS. Measles in 2019 — Going Backward. N Engl J Med. 2019;380(23):2185-2187. doi:10.1056/NEJMp1905099
11. Larson L, Wynn S, Schultz RD. A canine parvovirus nosode study. In: Proceedings of the Second Annual Midwest Holistic Veterinary Conference 1996. ; 1996.
12. Loeb M, Russell ML, Neupane B, et al. A randomized, blinded, placebo-controlled trial comparing antibody responses to homeopathic and conventional vaccines in university students. Vaccine. 2018;36(48):7423-7429. doi:10.1016/j.vaccine.2018.08.082
13. McKenzie BA. Assessing claims of vaccine-induced ITP, IMHA. Vet Pract News. 2018:32-33. https://www.veterinarypracticenews.com/assessing-claims-of-vaccine-induced-itp-imha/. Accessed January 10, 2020.
14. Centers for Disease Control and Prevention. MMR Vaccination | What You Should Know | Measles, Mumps, Rubella | CDC. https://www.cdc.gov/vaccines/vpd/mmr/public/index.html. Accessed January 10, 2020.
15. Althaus CL, Salathé M. Measles vaccination coverage and cases among vaccinated persons. Emerg Infect Dis. 2015;21(8):1480-1481. doi:10.3201/eid2108.150284
16. Kim TH, Johnstone J, Loeb M. Vaccine herd effect. Scand J Infect Dis. 2011;43(9):683-689. doi:10.3109/00365548.2011.582247
17. McKenzie B. Veterinary Homeopathy: Why are we still talking about this? Vet Pract News. December 2019:34.