Message of Vaccine Acceptance Can Boost Immunization Rates

The development of a COVID-19 vaccine signaled, for many, the long-awaited light at the end of the tunnel. But for the vaccine to be effective in ending the pandemic, a large majority of the population – some estimates put it at more than 75% – have to be willing to get it.

And that might prove to be the tricky part.

While hesitancy to get a vaccination makes headlines, new research finds that emphasizing the widespread and growing acceptance of the vaccine is an effective way to encourage more people to get immunized.

“Our research has shown that giving people accurate descriptions of norms in their communities, like how many people are accepting the vaccine, makes them more willing to get it themselves,” said Amin Rahimian, assistant professor of industrial engineering at the University of Pittsburgh Swanson School of Engineering and co-author of the study, which is currently under peer review. “This knowledge presents an important opportunity for public health officials to effectively communicate.”

The study, led by MIT Sloan School of Management professors Sinan Aral and Dean Eckles, highlights the importance of messaging in reaching the goals of widespread vaccination, herd immunity and the eventual eradication of COVID-19. As part of a larger collaboration with Facebook and using input from public health experts at Johns Hopkins University, the Global Outbreak Alert and Response Network (GOARN), and the World Health Organization, the researchers fielded a survey with over 1.9 million responses from 67 countries in their local languages.

On a sample of more than 400,000 people in 23 countries, the researchers surveyed the participants about their plans for vaccination, inserting information throughout the survey about others’ behavior. When given accurate information about the number of people who said they’d receive the vaccine, the number of people who were unsure or felt negative about accepting the vaccine was reduced by 5 percent.

“Everyone has different reference points when it comes to societal norms, but overall, peoples’ preventative health behaviors are dramatically influenced by social and cultural factors,” said Rahimian. “The most important message is to appreciate the value of these norms. It is natural for people to be hesitant, but emphasizing overall acceptance is an important way to contextualize the decision they’re making for themselves and their community.”

Because one cannot tell by looking at people whether they’ve been immunized, messaging around acceptance rates is an especially potent tool to encourage more participation. The researchers noted that it wasn’t clear going into the study whether learning that more people were vaccinated would encourage or decrease acceptance of the vaccine. For example, if a majority of others say they will get it, some people may think it’s safe to skip it.

“Humans are sensitive to the behaviors of others. Public health communications should avoid overemphasizing the shrinking minority of people who say they won’t accept a vaccine against COVID-19,” said Eckles. “The best way forward, as is often the case, is the presentation of clear, accurate and timely information. That includes the information that other people overwhelmingly intend to accept these vaccines.”

The Age of Data

Rahimian’s work is at the intersection of networks, data, and decision sciences. His work focuses on analysis and decision making in large-scale, sociotechnical systems, like social media, and the opportunities it represents for researchers.

“The landscape for scientific research is changing in the age of data. The combined force of high-end data analytics and high performance computing opens new ways for scientific discovery,” said Rahimian.

In this project, the researchers partnered with Facebook to gather data. The survey was deployed through the social media platform, and the researchers received anonymized responses attached only to a participant number. The partnership gave them extraordinarily detailed information on the participants’ demographic data along with their responses, without revealing their identity.

“It was very important for us to make sure our survey was representative of the population. Facebook is in a unique position to help with this kind of work because of the massive amount of demographic and behavioral data that they can use globally,” Rahimian said. “Ensuring that we are hearing from a lot of different kinds of people allows us to extrapolate better conclusions about the population as a whole.”

The paper, “Surfacing Norms to Increase Vaccine Acceptance,” (Preprint DOI: 10.31234/osf.io/srv6t) is undergoing peer review and was co-authored by Alex Moehring, Avinash Collis, Kiran Garimella, M. Amin Rahimian, Sinan Aral and Dean Eckles.