Vaccine Hesitancy and Herd Immunity

Vaccine hesitancy is the term used to describe a delay in acceptance or refusal of vaccines, despite the availability of the vaccination. Factors that are involved in vaccine hesitancy include complacency, convenience, and confidence (World Health Organization, 2016). As of June 2021, using survey data based on if respondents would “definitely not”, “probably not” or “unsure” about receiving the vaccination, the Centers for Disease Control and Prevention (CDC) estimated the hesitancy rates for the COVID-19 vaccination. The results show a range in estimated hesitancy for each state, with lows around 2.7% and states as high as 26.7% hesitancy rates (CDC, 2021).

Herd immunity is achieved when a threshold of a population becomes immune to a specific disease through immunization or contracting and recovering from the infection. The thresholds for obtaining herd immunity vary by the specific disease. Measles, for example, requires at least 95% of the population to be immune for herd immunity and to stop transmission of the disease. For COVID-19, it is unknown what percentage of the population is required for the threshold of herd immunity (Desai & Majumder, 2020).

Immunity can occur by natural infection through contracting the disease. An individual can develop antibodies, but the disease can negatively impact a person’s overall health, which can increase morbidity and mortality. There is also a chance of becoming re-infected with the disease. Vaccination against a disease can provide protective antibodies without causing illness or related complications. Diseases that have been successfully controlled by herd immunity through immunizations include polio, rubella, smallpox, and diphtheria, among others (Mayo Clinic, 2021).

With the current vaccine hesitancy rates for the COVID-19 vaccine in the United States, it may be difficult to achieve more than 70% immunity for the population. This can severely decrease the likelihood that herd immunity can occur for COVID-19 (CDC, 2021; Desai & Majumder, 2020; Mayo Clinic, 2021). As healthcare providers, it is our responsibility to educate patients to increase overall confidence in receiving the vaccination. With each patient immunized, we are one step closer to achieving herd immunity.

^References:

^{Centers for Disease Control and Prevention. (2021). Estimates of vaccine hesitancy for COVID 19.  Desai, A., & Majumder, M. (2020). What is herd immunity? JAMA, 324(20), 2113.}

^{Mayo Clinic. (2021). Herd immunity and COVID 19 (coronavirus): What you need to know.} 

^{World Health Organization. (2016). Vaccine hesitancy: What it means and what we need to know in order to tackle it.}