Why Vaccines Work

Pharmacy TimesSeptember 2018 Immunization
Volume 84
Issue 9

Edward Jenner created the first vaccine to protect against smallpox in the 1790s.1 Since then, the pathway to effective and safe vaccines has not been direct or easy, yet millions of lives have been saved, proving that vaccines, in general, are powerful medical interventions.1

Edward Jenner created the first vaccine to protect against smallpox in the 1790s.1 Since then, the pathway to effective and safe vaccines has not been direct or easy, yet millions of lives have been saved, proving that vaccines, in general, are powerful medical interventions.1

Vaccines work. Take, for example, diphtheria, which was a major cause of death and illness among children before immunization. There were 206,000 recorded cases of diphtheria in the United States in 1921, resulting in 15,520 deaths, before immunization was available.2 A vaccination became available in the later 1920s, and cases of diphtheria have declined since, with just 2 recorded cases in the United States between 2004 and 2015.2

Other examples include the elimination of polio and smallpox from the United States.3,4

Elimination of a disease means that there is no year-round transmission. However, sometimes a traveler will bring the disease into the United States from another country.

According to the CDC, vaccine-preventable diseases have declined dramatically from the prevaccine eras. In addition to the instances of diseases listed above, cases of hepatitis A, measles, mumps, pertussis, rubella, tetanus, and varicella have decreased by more than 90%. Instances of other diseases have decreased by 70% to 89%.5


By age 2, children in the United States are required to have 16 to 20 doses of vaccines, yet 20% of US children are deficient in 1 or more recommended immunizations.6 Several reasons exist for these low immunization rates. Lack of education is the primary one. Parents sometimes do not understand what it takes to get their children fully vaccinated and are unaware of what vaccines are available. Also, it has been decades since the United States has seen the devastation that these diseases can cause.

Another cause of low immunization rates is vaccine hesitancy. The Strategic Advisory Group of Experts on Immunization says that “vaccine hesitancy refers to delay in acceptance or refusal of vaccination, despite availability of vaccination services. Vaccine hesitancy is complex and context specific, varying across time, place, and vaccines. It is influenced by factors such as complacency, convenience, and confidence.”7

Confidence is a 3-part concept. The trust that the vaccine is effective, necessary, and safe is paramount.7 In addition, the health care providers involved in the vaccination process must be competent and reliable.7 Finally, the motivations of policy makers, who decide on recommended vaccines, must be transparent.7

The Anti-Vaccination Movement: Personality Traits as Contributors

Complacency arises when perceived risks of disease are low and, as a result, vaccines are deemed unnecessary. Complacency is influenced by several factors, including the perception that there are other health and/ or life responsibilities that take precedence.7 Weighing the risk of adverse reactions of the vaccine versus the potential of acquiring the disease itself may also result in complacency.7

Convenience refers to physical accessibility and availability, as well as affordability and willingness to pay.7 Other contributing factors include time, place, and comfort of the venue.7 Pharmacists have made great strides in this area, as they can provide easy and quick vaccinations on a walk-in basis.


There is no 1 strategy to address vaccine hesitancy. The most effective interventions are multifaceted.8 To better identify factors influencing hesitancy, the World Health Organization/Europe has developed The Guide to Tailoring Immunization Programmes.8 It includes proven methods and tools to identify vaccine-preventable conditions and disease-susceptible populations, highlighting supply-and-demand barriers and enablers and recommending evidence-based responses to build and sustain vaccination rates.8

The pharmacist is an accessible and knowledgeable agent who can help dispel false claims about vaccines and address vaccine hesitancy on a case-by-case basis. Because pharmacists are one of the most trusted professions in the United States, patients often seek knowledge from them and trust that their pharmacist is fair, honest, and impartial and has their best interest at heart.


For the past 2 years, the influenza vaccines’ effectiveness has been relatively low. For this reason, there are questions regarding the role of the egg-based production process used for most vaccines. Some studies have demonstrated that mutations can occur during the process, reducing the efficacy of the vaccine by 50%.9

Recombinant influenza vaccine, a non-egg-based product, has been well established in adults but not children. A recent randomized controlled trial compared the efficacy and safety of the quadrivalent, recombinant influenza vaccine (RIV4) with the inactive influenza vaccine in children aged 6 to 18.10 This study concluded that the efficacy and safety of RIV4 were comparable to that of the inactive influenza vaccine in this age group.10 Confirmatory studies are needed to support the use of recombinant influenza vaccine as an alternative for children 6 years and older.10

A high-dose flu vaccine has been approved for use in people 65 years and older for some time, but neither the CDC nor public health officials express a preference for which vaccine should be given in this age group. A recent meta-analysis reviewed the relative efficacy of high-dose inactivated trivalent influenza vaccine and standard-dose influenza vaccine in adults 65 years and older.11

The authors of this study concluded that available evidence suggests high-dose inactivated influenza vaccine is more effective than standard-dose influenza vaccine at reducing clinical outcomes associated with influenza infection in older adults and should be considered for routine use in the 65-plus population.11

Kathleen Kenny, PharmD, RPh, earned her PharmD from the University of Colorado Health Sciences Center in Aurora. She has more than 25 years of experience as a community pharmacist and is a freelance clinical medical writer based in Colorado Springs, Colorado.


  • Stern AM, Markel H. The history of vaccines and immunization: familiar patterns, new challenges. Health Aff (Millwood). 2005;24(3):611-621. doi: 10.1377/ hlthaff.24.3.611.
  • Diphtheria. CDC website. cdc.gov/diphtheria/clinicians.html. Updated January 15, 2016. Accessed July 29, 2018.
  • Polio elimination in the United States. CDC website. cdc.gov/polio/us/index.html. Updated November 28, 2017. Accessed July 29, 2018.
  • Smallpox. CDC website. cdc.gov/smallpox/clinicians/clinical-disease.html. Updated December 5, 2016. Accessed July 29, 2018.
  • Vaccines work! Immunization Action Coalition website. immunize.org/catg.d/ p4037.pdf. Accessed July 29, 2018.
  • Low immunization rates. CDC website. cdc.gov/healthcommunication/ toolstemplates/entertainmented/tips/LowImmRates.html. Updated February 15, 2011. Accessed July 28, 2018.
  • MacDonald NE, SAGE Working Group on Vaccine Hesitancy. Vaccine hesitancy: definition, scope and determinants. Vaccine. 2015;33(34):4161-4164. doi: 10.1016/ j.vaccine.2015.04.036.
  • Addressing vaccine hesitancy. World Health Organization website. who.int/immunization/programmes_systems/vaccine_hesitancy/en/. Updated June 27, 2018. Accessed July 28, 2018.
  • Analysis argues that egg production keeps flu vaccine efficacy low. US Pharmacist. uspharmacist.com/article/analysis-argues-that-egg-production-keeps-flu-vaccine-efficacy-low. Published June 27, 2018. Accessed July 25, 2018.
  • Dunkle LM, Izikson R, Patriarca PA, Goldenthal KL, Cox M, Treanor JJ. Safety and immunogenicity of a recombinant influenza vaccine: a randomized trial. Pediatrics. 2018;141(5). doi: 10.1542/peds.2017-3021.
  • Lee JKH, Lam GKL, Shin T, et al. Efficacy and effectiveness of high dose versus standard dose influenza vaccination for older adults: a systematic review and meta-anal- ysis. Expert Rev Vaccines. 2018;17(5):435-443. doi: 10.1080/14760584.2018.1471989.

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