Third Time's the Charm? Vaccine Hesitancy and the Booster Dose

Hartej Gill, PhD(c)


December 13, 2021

"Are you getting the third dose?" I have been asked this question countless times within the past few weeks. Many countries are moving toward recommending a third dose, or booster shot, for individuals who have been fully vaccinated. In the United States, the US Food and Drug Administration has recommended emergency authorization for a booster dose of the Moderna and Pfizer-BioNTech COVID-19 vaccines for anyone aged 18 years or older.

Similarly, Canada's National Advisory Committee has recommended the mRNA vaccines for a third (or booster) dose. The European Union has followed similar recommendation guidelines for their member countries. However, many in the general population have expressed hesitancy regarding the adverse events and additional benefits of a booster dose. Growing confusion and distrust in authority figures is likely an important contributing factor for this vaccine hesitancy.

In recent months, we have seen a steady increase in vaccination numbers across the globe. In the United States, nearly 60% of all people ages 12 years and older have received two doses of the FDA-approved vaccines. In Canada, approximately 80% of the population aged 12 years and older has received at least one dose and approximately 75% has received both doses.

Growing Distrust

Of note, the two countries took a different approach with their vaccination strategy. In Canada, we saw the first dose prioritized, and the wait times for the second dose extended. In many cases, this led to a 4-month wait between the first and second dose — a number far greater than the 21 days recommended by the vaccine developers. Among family and friends, there was growing frustration due to prolonged supply shortages and a confusing booking system.

I was faced with many vaccine-related questions: "Is the vaccine safe to take?" "What is the best vaccine?" I do not have an epidemiology or immunology background aside from a few undergraduate courses. However, for many within the science community, friends and family relied on us for vaccination knowledge dissemination.

The feeling stemmed from a general distrust or confusion in the government's vaccination policies and guidelines. For example, the AstraZeneca Vaxzevria COVID-19 vaccine is approved in Canada. During the early stages of Canada's vaccination program, the AstraZeneca vaccine was met with far greater hesitancy compared with the mRNA vaccines. The concerns stemmed from early reports related to thromboembolic events. In an effort to promote the safety and efficacy of the AstraZeneca vaccine, many political leaders, including the Canadian Prime Minister, received the AstraZeneca vaccine for their first dose. But as concerns related to efficacy and tolerability grew among the general public, the government shifted course.

Now, the recommendations advise that individuals who received the AstraZeneca shot for their first dose should instead receive the Pfizer or Moderna vaccine for their second dose. In fact, preliminary literature suggested that mixing and matching vaccines may produce a more potent immune response, but the change in policy added to the growing feeling of distrust in the vaccination guidelines.

Because of the incredible pressure to get a vaccine out, concerns regarding efficacy and tolerability were always inevitable. However, it may have been just as important to avoid a public mistrust of science. Trust-building measures needed to extend beyond clinical findings surrounding the efficacy and tolerability of vaccines. For example, recent antivaccine protests were organized in front of Canada's largest hospital network. Indeed, vaccine hesitancy should receive greater attention and may be an important factor for building a positive relationship between the general public and our healthcare system.

Vaccine Hesitancy

Vaccine hesitancy is not a novel phenomenon. Even prior to the emergence of COVID-19, the reemergence of measles in the United States and other developed countries highlights the growing feelings of hesitancy toward immunization.

A number of possible factors may play a role in predicting instances of increased hesitancy. A comprehensive review of academic and gray literature describing attitudes toward vaccination highlighted age, education, parental status, rurality, mistrust of authority, and sensitivity to disgust as notable predictors of vaccine hesitancy.

Of interest, younger adults reported higher levels of hesitancy relative to middle-aged and older adults, with a key mediator being reliance on information found on social media. Further, concerns from healthcare providers surrounding the overuse of vaccines play a major role in influencing the opinions of postpartum mothers on vaccination. Meanwhile, other individuals report hesitancy resulting from mistrust in government bodies or medical professionals. This subset of the population tends to rely more heavily on relatable sources of information, such as peers and community leaders.

Hesitancy to Acceptance

Unlike antivaccination ideologies, vaccine hesitancy is more dynamic and exists on a spectrum. Due to the varying degree of and reasons for hesitancy surrounding immunization within communities, intervention and prevention methods for reducing this hesitancy should target specific reasons for the vaccine-hesitant attitudes. For example, efforts may be made to push younger adults to seek evidence-based knowledge instead of social media posts.

Collaboration between medical health professionals, community leaders, and peers may be facilitated to offer individuals with distrust in authority or governing bodies a more relatable and trustworthy source of accurate information. Peer-led interventions have demonstrated efficacy in a number of healthcare related areas, such as substance abuse and HIV prevention interventions. Indeed, there is not a single solution to reduce vaccine hesitancy. An open dialogue to improve scientific knowledge dissemination and translation is an important first step.

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About Hartej Gill
Hartej Gill is a PhD candidate and researcher at the Canadian Rapid Treatment Center of Excellence and the Institute of Medical Science at the University of Toronto. He has expertise in mood disorders, investigating the etiology and pathophysiology of mental health disorders from both a clinical study and population health perspective, with over 50 peer-reviewed publications.


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