Pharmaceuticals & Biotech

A cognitive research playbook for encouraging hesitant consumers to get COVID-19 boosters

By Jacob Braude, Marta Biase, Palak Gupta, Surbhi Goel, and Srujan K.

Nov. 15, 2022 | Article | 11-minute read

A cognitive research playbook for encouraging hesitant consumers to get COVID-19 boosters

Looking back at the initial release of the COVID-19 vaccine in the summer of 2021, we see a far different picture than we do today. The industry was learning how to manage the vaccine’s logistics by trial and error. Demand for vaccines far outstripped supply. Consumers obsessively checked retail drugstore websites looking for an opportunity to sign up for their first dose. Long lines of people wrapped around community clinics in the hopes they could get the vaccine that meant freedom from future lockdowns.


Now, many medical facilities have more doses than they do people to give them. A subset of those who rushed to get their first dose haven’t followed up on the series after their initial shot. Major restrictions in travel have ended, and mask mandates have fallen away.


As health organizations begin to consider when COVID-19 might move from pandemic to endemic, we see attitudes and behaviors emerging that could affect how quickly it achieves its endemic status. Will COVID-19 be another illness that people get boosted for each fall, just as they get their annual flu shots?

COVID-19 boosters could use a boost

The trouble is, that doesn’t seem to be happening. Where we might have expected some excitement around the introduction of the bivalent vaccine from Pfizer and Moderna in August 2022, interest seems to be flat—despite its promise to address the BA.4 and BA.5 omicron variants that sickened large populations around the world in 2022. Booster coverage continues to lag in the U.S., where just over 22 million people have received their updated bivalent dose, just 7.3% of the eligible population so far.


The healthcare industry has some work to do to help encourage the levels of worldwide immunity required to be able to truly call COVID-19 endemic. Even if it does attain this status, we know from our research on parents hesitant to vaccinate their children against certain illnesses that outbreaks of previously managed conditions can happen at any time when a population’s immunity is weakened.


As an extension of our ongoing cognitive research, we set out to better understand those who are hesitant to take their next COVID-19 booster, even though they have already received at least one dose of their COVID-19 vaccine.

About our 2022 COVID-19 booster hesitancy research

In the summer of 2022, we surveyed 4,083 adults in the U.S., Brazil, Canada, France, Germany, Italy and the U.K. These individuals were required to have completed, at minimum, their first dose of the COVID-19 vaccine series and at maximum, up to two boosters following their first dose. Yet they identified themselves as hesitant toward getting their next COVID-19 booster when it is recommended for them. Participants represented a mix of age, gender, income, living locations (e.g., urban, suburban or rural) and employment statuses.


Those who qualified were presented with two scenarios. If they only expressed hesitancy in one scenario, they were placed in a survey on that one. If they expressed hesitancy in both scenarios, they were randomly assigned to a survey on one of the two:


COVID-19 urgent scenario: A new COVID-19 variant has emerged. COVID-19 cases and hospitalizations are rising in your country.


COVID-19 declining scenario: COVID-19 cases have been decreasing steadily in your country. The government has removed mask mandates for the time being and life feels “back to normal.”


Of this booster-hesitant group, the majority had received the Pfizer Comirnaty vaccine (70%), with the second-largest group receiving the Moderna Spikevax vaccine (32%). Despite the fact these consumers had already been vaccinated, they held some common concerns about COVID-19 vaccines. For example, 14% expressed fears associated with the vaccine, ranging from basic uncertainty (“playing with fire”) to the idea that the vaccine is “poison” or “death on installments.” Another theme that arose was the idea that each COVID-19 vaccination is analogous to gambling or a situation where they were unsure of what would result from taking it.


The goal of our research was to identify the attitudes and cognitive factors influencing these consumers while testing which interventions would encourage them to receive additional COVID-19 vaccine boosters when they are eligible.

How to use these cognitive factors to encourage COVID-19 booster vaccines

Our research supports that consumer confusion and uncertainty about COVID-19 and vaccines remains. This situation is not necessarily an education issue because so much educational information already exists on this subject. Resolving this issue will require the healthcare industry to help consumers focus on the most pertinent factual information that removes ambiguity and supports their decision-making process.


Regardless of whether it was a COVID-19 urgent or declining scenario, our research identified how important it is to help consumers focus on the facts and reinforce the value of booster vaccines. When in a declining scenario, it’s of critical importance to deliver frequent, effective reminders to consumers to motivate them to overcome the perceived effort of getting a COVID-19 booster. If rising cases and deaths are a top news story, this environment naturally generates a sense of urgency. Yet if it feels like society has returned to normal and everyone is healthy, getting a booster isn’t perceived as necessary.

Successful approaches when COVID-19 cases are rising

An effective approach to prioritize in this scenario is to reinforce the value of COVID-19 boosters. We found these three cognitive factors emphasized this message:

  • Affect Heuristic: Evoking positive emotions for consumers (for example, making them happy, hopeful or inspired), may make them more willing to get their next COVID-19 booster. This approach drove a global change of 11% of hesitant to willing participants, particularly in Canada, France, Germany and Italy. We saw the highest impact from this factor in the income group with low-income participants.
  • Embodied Cognition: Using familiar metaphors expressing the idea of added protection may encourage consumers to get a booster. For example, some descriptions compared the COVID-19 booster to wearing a bulletproof vest or multiple helmets on a construction site. This increased a positive response by 24% and a confident response by 19% across participants in all six participating countries. It was not active in Italy in a rising case scenario.
  • Moral Regulation: Reminding consumers with the framing that getting a COVID-19 booster is a morally right thing to do helps drive booster acceptance by a global change of 39% from hesitant to willing participants. This result held true across all ages, genders, incomes and employment statuses globally.

Focusing on the facts also helped resolve certain beliefs among hesitant individuals. These two cognitive factors had the greatest effect within this approach:

  • Ambiguity Aversion: Participants who saw scientifically backed information that cited no long-term health effects as a result of taking multiple boosters increased their willingness to receive the next booster by 7% globally. They showed a global 5% change from hesitant to willing after seeing increased hospitalization rates among the vaccinated but not boosted population. This cognitive factor was active in all seven countries included in this study.
  • Satisfaction of Search: Participants who had a checklist of COVID-19- related information that included safety data, side effect information and more increased their acceptance of boosters by 11% globally. Having the information they needed in their hands motivated them to make their decision to get the booster.

In this scenario, the most effective approach to prioritize is to remind, remind and remind again. These three cognitive factors actively worked to support this strategy:

  • Mere Measurement Effect: The more individuals are reminded to take an action, the more likely they are to take this action. Considering signing up to receive a COVID-19 booster multiple times can increase a hesitant consumer’s willingness to get a booster. This drove a global 27% change from being hesitant to willing in all seven participating countries.
  • Effort Justification: Positioning the booster as a continued effort to maintain immunity against and safety from COVID-19 makes it seem more appealing, inspiring a 22% change in hesitant to willing across all seven participating countries. It’s worth noting that Effort Justification also encouraged hesitant individuals to get their first vaccine in our 2021 COVID-19 vaccine hesitancy research.
  • Outcome Bias: Reminding consumers of the positive outcomes of COVID-19 vaccination and boosters increases their willingness to get their next booster, with a global 8% change from hesitant to willing. This factor was active in Brazil, France, Germany and Italy, but not in Canada, the U.S. and the U.K.

Similar to the scenario where COVID-19 cases are rising, reinforcing the value of boosters also drove results when COVID-19 cases are declining. The same three cognitive factors were active, but with higher global percent changes:

  • Affect Heuristic: This approach also drove a global change of 11% of hesitant to willing participants, particularly those in Brazil, Canada, Germany and the U.K. This factor was not active in France, Italy or the U.S. in the declining scenario.
  • Embodied Cognition: Making comparisons between COVID-19 boosters and similar actions you’d take for safety encouraged consumers to get a booster, increasing a positive response by 30% and a confident response by 24% across participants in all seven countries and across all subgroups globally.
  • Moral Regulation: Reminding consumers through framing that getting a COVID-19 booster is a morally right thing to do helps drive booster acceptance by a global change of 48% from hesitant to willing. The effect of this factor was highest in France, with 59% of participants more willing to get a booster as a result of this framing.

A focus on the facts approach also worked for the scenario when COVID-19 cases were declining, though with slightly lower results than reminding and reinforcing the value of boosters.

These cognitive factors failed to encourage adults to get a COVID-19 booster vaccine

In both the urgent and declining scenarios, six of the cognitive factors we tested did not work to encourage booster-hesitant individuals to get another dose, including Choice Supportive, Ego Depletion, Overconfidence Effect and these three:


Failed – Social Facilitation: The presence of others can promote accountability and improve judgement when individuals feel others are judging their actions. Although this cognitive factor was active in our 2021 COVID vaccine research, it did not affect participant behavior in this booster study. We believe this may be due to the shift in attitudes toward COVID-19 as it becomes normalized and less scary than it once was.


Failed – Social Norms: People are influenced by accepted attitudes and behaviors within a particular group, community or culture. Though it seems counterintuitive in what feels like a world divided by tribal attitudes, this factor had no influence over whether an individual would get a booster.


Failed – Loss Aversion/Gain Frame: An individual’s comfort with risk is influenced by whether the choice is framed as a loss or a gain. This framing did not move the needle to change attitudes or behaviors related to getting a COVID-19 booster.

Steps to take to encourage individuals to keep up with their COVID-19 vaccinations globally

Thinking back to what the world looked like when the first COVID-19 vaccines were released in the summer of 2021, we have things much more under control now than we did then. Deaths due to COVID-19 were trending down in October 2022, as were hospital admissions of confirmed COVID-19 patients. In many ways, life is returning to what feels much closer to a pre-pandemic normal.


It’s not possible to remove all ambiguity related to COVID-19, its vaccines and boosters. But we do know that it’s possible for the healthcare industry to develop effective strategies that weave together reinforcing the value of a booster, focusing on the facts and offering frequent reminders to drive behavior change and increase global immunity. Simple tactics such as creating a “need to know” checklist for individuals to see before getting a booster or communicating the value of a booster in terms familiar to customers, such as “it’s like wearing a seat belt,” are effective ways to inspire action.


As the world continues to ride the waves of new variants and cases, our research offers a playbook that weaves together these active cognitive factors into outreach campaigns, communications and more, to reach those individuals in various countries who may be keeping the pandemic alive.

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