Big Shot

Using Trump’s endorsement to boost vaccinations

Screenshot of Fox News showing Donald Trump's picture on the left and a hand holding a syringe on the right. Closed captioning of Trump's words reads: But it's a great vaccine, it's a safe vaccine.

While health officials have struggled to boost COVID-19 vaccination rates nationwide, a simple approach has proven effective at convincing some skeptics to get their shots: a video compiled from Fox News clips of former President Trump and his family urging his supporters to get vaccinated.

Researchers from Berkeley Haas, Stanford University, University of North Carolina at Chapel Hill, and North Carolina State University compiled a public service announcement from existing footage and aired it on more than 150,000 YouTube channels in more than 1,000 U.S. counties with vaccination rates below 50%. Compared with similar counties where the ad wasn’t shown, those counties recorded an additional 104,036 vaccinations.

While the researchers had no control over which channels the ad would appear on, the Google Ads’ algorithms sent it most often to Fox News’ YouTube channels, where it was attached to segments hosted by Laura Ingraham, Tucker Carlson, Sean Hannity, and other Trump supporters and vaccine skeptics. It also appeared on some neutral channels and some not supportive of Trump, including MSNBC and NBC News.

According to Professor Steven Tadelis, a co-author, the messaging was also relatively inexpensive. “Creating an intervention that effectively costs about $1 per extra vaccine is remarkably cost-effective and a small fraction of the cost of other interventions,” he says, noting that studies of U.S. state vaccine lotteries put the cost at $68 to $82 per vaccine.

However, while the ads moved some skeptics to action, they were only effective in counties with up to 70% Trump voters. The heaviest pro-Trump counties were unmoved.

YouTube channels where ads were placed

Graph showing that the ad appeared most on Fox News followed by Forbes Breaking News. The ad appeared least on CNBC.

Percent of unvaccinated Republicans expressing a “great deal of confidence” in vaccine advice from specific sources

Bar graph showing increasing confidence in Donald Trump but waning confidence in Joe Biden, Anthony Fauci, personal doctors, or the scientific community.

Geographic distribution of advertising campaign by county

Map of the United States with counties colored to show one of the following: low saturation, high saturation, control counties, or excluded counties (because of high vaccination rates, large population, or poor CDC records).