After COVID-19 vaccines were made available to the public last winter, millions of people lined up in anticipation to get the jab.

But by summer 2021, vaccine hesitancy across communities deferred progress, and the number of people getting vaccinated nationally has hovered at roughly 64% since.

To address the issue, in September, nonprofit The Ad Council partnered with creative ad tech company Artsai to develop personalized campaigns targeted at residents in vaccine hesitant states including Missouri, Mississippi, Florida, Nevada, Arkansas and Louisiana.

By tapping into Artsai’s predictive-personalization technology, the Ad Council delivered personalized creative assets that aimed to increase visits to, as well as the ImmunizeNV website in Nevada.

As part of the six-week campaign, Artsai and the Ad Council developed nine ads, each with unique messaging and personalization elements, that would speak to the diverse populations of each state.

Messages varied, with some highlighting the case levels in each state or the free nature of vaccines, while others focused on hospitalization rates or encouraged people to protect their loved ones by getting vaccinated. Visual assets were optimized with different color backgrounds, state images and photos based on user data.

Artsai’s platform used AI to learn how different people reacted to each piece of creative and optimized the message for greater effectiveness, said Erik Lundberg, chief revenue officer at Artsai.

Artsai also detected hidden patterns in the data. For instance, in Nevada, the strongest performing call-to-action text was “COVID-19 vaccines are free and available near you.” That differed from other states, where “Get the facts on COVID-19 vaccines” was the top performing CTA.

Artsai found that the most important elements affecting campaign performance included what website a user was visiting when they saw the ad; the city or state the user was in when they saw the ad; their time zone and whether they were on a computer or a mobile device.

The insight allowed the Ad Council to pivot accordingly, to generate more clicks on websites and, ultimately, get more jabs in arms, said Rex Briggs, founder and executive chairman of Marketing Evolution Inc. and Ad Council member.

“Early on, we tried a message about getting back to normal. Then we tried a more complicated message about parents protecting kids, and we quoted how many children had lost a parent to COVID,” he said. “[What worked and where it worked] was an insight that we would have only learned by using AI to test and learn at a massive scale.”

By allowing internet users to see messages that resonated most with them, the campaign drove 39.6% more people to visit than standard creative. In Nevada, the number of visits to the ImmunizeNV website jumped 70%.

Overall, the campaign drove more than 60,000 visits to the website, resulting in more than 25,000 incremental vaccinations.

“There’s so much diversity in our country and in our world. We should embrace that with communications that meet people where they are,” Briggs said. “We need technology to do that at scale.”

This article originally appeared on PRWeek US.