When compared to counties that did not receive the ads, those that did receive the ads had more than 100 additional vaccinations on average. In total, treatment counties received an estimated 104,036 more vaccines than control counties. The analysis also found that for every 1,000 more ads presented, there were nearly nine additional vaccinations, on average, per county.
However, the ad’s effect waned with increasing strength of Trump’s base. Researchers found that in counties where more than than 70% of voters supported Trump, the ads did not change vaccine uptake.
Marc Hetherington, an author of the study and professor of political science at the University of North Carolina, Chapel Hill, was conducting surveys to assess people’s attitudes towards the pandemic when it first hit the US in 2020.
“What we started to realize at that point is this is turning into a highly politicized pandemic of all things,” he said. “Public health people are probably not used to coming up with solutions to health problems that are politicized.”
Overall, the researchers spent $100,000 in ads that reached 6 million viewers, costing about $1 per additional vaccine received. The ad campaign ran from October 14, 2021 to October 31, 2021, after Trump was no longer in office. The ad was featured on a diverse array of YouTube channels, including NBC News, Fox News and Saturday Night Live.
“We found in our survey work that unvaccinated Republicans … had more confidence in Donald Trump than even their own family doctor when it came to providing advice about vaccines,” Hetherington said.
The ad opens with a segment from a Fox 13 News Utah anchor who says, “Donald Trump is urging all Americans to get the Covid-19 vaccine.”
A Trump interview on Fox News follows: “I would. I would recommend it. And I would recommend it to a lot of people that don’t want to get it, and a lot of those people voted for me, frankly,” he says about the vaccine in the ad. The ad also features a quote from Ivanka Trump with a photograph of her receiving the vaccine.
The ad also linked to a full interview between Trump and Fox News anchor Maria Bartiromo from March 16, 2021 — a clip of which was featured in the ad.
Due to the algorithms used by YouTube’s advertising platform, Google Ads, the researchers could not control exactly who received the ads within the treatment counties. Not all counties that were assigned as treatment counties received the ads, though the analysis was based on whether they were intended to receive the treatment.
“This politicization of the Covid vaccine is leaking over into people’s attitudes about vaccines more generally,” Hetherington said. “For public health professionals, they’re going to probably need to take politics into account, not just about the Covid vaccine, but about other vaccines in the future.”