St. Paul, Minn. — The urge to help end the pandemic through promoting vaccination has led many health professionals, professors, government agencies, and others to create vaccine explainer videos for YouTube, TikTok and other social media platforms. Yet there is little evidence and research about whether such videos actually affect someone’s propensity to get vaccinated.  

A new preprint study, from Professors Leah Witus and Erik Larson looking at one such vaccine education video, reveals the answer is yes, these videos can have an effect, but it’s not always a positive one, depending on who is delivering the message and who the audience is. 

Witus and Larson’s study examines two versions of an eight-minute, animated, educational YouTube video on the COVID-19 mRNA vaccines that they created called “COVID19 mRNA vaccines explained.”  One version of the video was narrated by a man and the other by a woman. The content of both videos is identical and explains how the mRNA vaccines work, highlights some of the positive features such as high efficacy and rarity of serious side effects, and emphasizes the altruism of vaccination.

After surveying 1,184 people in the United States, they found that people who watched the video were more inclined to express intention to be vaccinated, but that the messenger matters.  The video with a male narrator had a robust association with increased vaccination intention, while the identical video with a female narrator had much more uneven associations, part of which could be accounted for by conservatives uniquely expressing uncertainty in vaccination intention after viewing the female-narrated version.

“Frankly, I was surprised by the results,” said Dr. Larson, a professor of sociology. “First off, there was significantly more intent to get vaccinated among people who watched one of the videos compared to those who didn’t see the video at all. That was interesting.” 

But even more interesting to the researchers were the responses to the female-narrated video. 

“We found much more variation in the responses,” said Dr. Witus, a professor of chemistry. “It turned out that for people who identified as conservative, watching the video with a female narrator, but not the video with the male narrator, actually had a little bit of a backfire effect.” 

Professors Witus and Larson highlighted some key takeaways: 

  • The “COVID-19 mRNA vaccines explained” YouTube video has evidence of increasing vaccination intention, and can be used as a tool in vaccine promotion for health departments or other groups working to overcome vaccine hesitancy as availability and access increase.
  • The study underscores that videos that attempt to increase people’s intention to get vaccinated should be tested because we do find that videos can work, but that for certain viewers they could lead to a reduced interest in getting vaccinated. 
  • There’s an ethical question here. We don’t want to reinforce stereotypes, but at the same time, getting vaccinated could save lives. 
  • In many ways, the idea that “A male voice is more authoritative, therefore we should use a male voice” reinforces the very problem that we point out. However,  we’re in a public health emergency and even though we feel uncomfortable saying it, we would recommend, if it’s a conservative audience, to go with the version of this video that has a male narrator.  
  • The implication is that we need more understanding about public trust in science, not just with science as an institution, but with scientists as individuals and who people see as the “voice of science.” 
  • Overcoming vaccine hesitancy was the original goal in making the video, but our results underscore that overcoming gender bias in science will be the next challenge, particularly since so many key developments in making the COVID-19 vaccines were accomplished by women, from Dr. Katalin Karikó to Dr. Özlem Türeci to Dr. Kissmekia Corbett.

It’s important to note that the study is currently under peer review. Given that the peer-review process could take months, and that this new information is highly relevant now, Drs. Witus and Larson felt it was prudent to share the results of their study while the review process is ongoing. 

Learn more about Macalester at

April 13 2021

Back to top