Pro-vaccine messages that appeal to community spirit or evoke the sense of embarrassment people would feel if they were to spread COVID-19 to friends and family are effective in persuading individuals to get vaccinated and encourage others to do the same, according to a new study conducted by researchers from the Center for the Study of American Politics at Yale University.
The study, published in the journal Vaccine, incorporates two survey experiments to gauge how a broad range of messages affect people’s intentions to get vaccinated, their willingness to persuade those they care about to get the shots, and their judgments of individuals who decide against receiving the vaccine.
Gregory Huber, Alan Gerber, and Scott Bokemper acknowledge that widespread vaccination remains the best option for controlling the spread of COVID-19 and ending the pandemic.
However, even though several successful vaccines have become available, hesitancy in the general population has the potential to limit their efficacy as a tool for ending the pandemic.
In the United States, the public’s willingness to receive a vaccine dropped from 72 percent saying they would be likely to get a COVID-19 vaccine in May 2020 to 60 percent of people reporting in November 2020 that they would receive a vaccine.
“Despite the considerable disruption the virus has caused to people’s lives, many people are still hesitant to receive a vaccine,” says the research team. “Without high rates of uptake, however, the pandemic is likely to be prolonged. Here we use two survey experiments to study how persuasive messaging affects COVID-19 vaccine uptake intentions.”
“Our work shows that messages emphasizing collective action on behalf of the community, combined with the notion of reciprocity, are effective in persuading individuals to say they will get vaccinated and encourage others to get the vaccine,” said Gregory A. Huber, the Forst Family Professor of Political Science in Yale’s Faculty of Arts and Sciences and a co-author of the study. “It also was interesting that emotional appeals, such as evoking embarrassment, motivate people to reach out to others. That second-level effect — encouraging others to get vaccinated — is likely very important to increasing the vaccination rate.”
In the first experiment, they tested a large number of treatment messages. One subgroup of messages draws on the idea that mass vaccination is a collective action problem and highlighting the prosocial benefit of vaccination or the reputational costs that one might incur if one chooses not to vaccinate.
“Prosocial” means behavior that is positive, helpful and intended to promote acceptance by the members of society.
Another subgroup of messages built on contemporary concerns about the pandemic, like issues of restricting personal freedom or economic security.
They found persuasive messaging that invokes prosocial vaccination and social image concerns is effective at increasing intended uptake and also the willingness to persuade others and judgments of non-vaccinators.
They replicated this result on a nationally representative sample of Americans and observed that prosocial messaging is robust across subgroups, including those who are most hesitant about vaccines generally.
These experiments demonstrate how persuasive messaging can induce individuals to be more likely to vaccinate and also create spillover effects to persuade others to do so as well.
By getting vaccinated, people protect themselves from a disease, but they also reduce the chance that they become a vector through which the disease spreads to others.
If enough people receive a vaccine, the population gains protection through herd immunity, but this also creates an incentive for an individual to not get vaccinated because they can forgo vaccination and receive protection from others who do vaccinate.
Recent research on vaccination, in general, has demonstrated that people view vaccination as a social contract and are less willing to cooperate with those who choose to inflict harm on the rest of the community by not getting inoculated.
Scholars and faculty from Yale’s School of Medicine, School of Public Health, School of Nursing, Department of Political Science, and the Institute for Global Health collaborated on the study with support from Yale’s Tobin Center for Economic Policy. By evaluating a series of messages in two successive experiments, Huber said, the study stands out from prior research that assessed the effectiveness of specific messages.
“It’s not enough to know if one message works; you want to know which messages work best,” he said. “With this study, we tested a range of messages, and then retested the ones that showed promise to see if they worked again. This is important because as the pandemic goes on, the people who avoid vaccination become increasingly difficult to persuade, so we need to know what works best and if our best messages continue to be effective.”
Participants in the first survey, fielded in July 2020, were randomly assigned to either a control group, which was presented a message on the effectiveness of bird feeders, or into groups that received one of 11 messages supporting vaccination. One of those groups read just a baseline informational message, which stated that getting vaccinated reduces the risk of contracting COVID-19 or spreading the virus to others. It also emphasized that the vaccines were safe and estimated to save millions of lives per year.
The other groups received the same baseline message along with one of 10 additional messages that took various approaches to persuasion, including: appeals to people’s self-interest or community interest; messages combining an appeal to the collective good with one of three emotions (guilt, embarrassment, or anger); statements concerning reputation and social image, such as the message about bravery and another about trusting science; and messages stating that vaccination is key to ending restrictions on personal freedom and economic activity implemented during the pandemic.
The second survey, conducted in September 2020, retested the baseline informational statement and the three best performing messages from the initial evaluation — which were those targeting community interest, embarrassment, and bravery — along with two revised messages concerning trust in science and personal freedom. It largely confirmed the results of the first survey, according to the authors.
“Vaccine acceptance research requires the same level of rigor and creativity as vaccine development research,” said Saad B. Omer, director of the Yale Institute for Global Health and co-author of the study. “This is one more example of faculty from various parts of Yale coming together to address a set of high priority questions in this pandemic.”
The simple informational message proved effective, increasing people’s intentions to get vaccinated by 6% over the control group in the nationally representative survey. The study showed that its efficacy was enhanced by adding language framing vaccination as a cooperative action aimed at protecting others, raising people’s intentions to get vaccinated by 10% over the control.
The message combining community interest with an appeal to the embarrassment an unvaccinated person would feel about getting others sick proved most effective in both surveys in motivating people to advise others to get the shots. It increased that intention by 14% over the control group among participants in the second survey.
In terms of provoking negative judgments of those who decline the vaccine, the messages urging people to trust the science and stating that refusing the vaccine is not brave were most effective in the second survey. While the message concerning science altered people’s beliefs about others who do not vaccinate, it was ineffective in getting people to change their minds about receiving the vaccine, the study showed.
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