Originally Published: 24 DEC 21 08:04 ET

Updated: 24 DEC 21 09:45 ET

By Ariel Edwards-Levy, CNN

(CNN) -- Former President Donald Trump has recently been vocal about the benefits of vaccination against Covid-19 -- a position that's in line with the overwhelming majority of Americans who've chosen to get vaccinated, including the bulk of his own party.

But those statements may not be enough to persuade the largely Republican-leaning group of holdouts who haven't yet gotten a shot, some research suggests.

During an event in Dallas last Sunday, Trump confirmed that he had been vaccinated and had gotten a booster shot, attracting boos from some audience members. In an interview released Tuesday, Trump stated his opposition to vaccine mandates but again touted the shot's efficacy. "The vaccine worked," he told The Daily Wire's Candace Owens. "But some people aren't taking it. The ones that get very sick and go to the hospital are the ones that don't take the vaccine."

While Trump didn't acknowledge it, most unvaccinated Americans now belong to or lean toward the GOP. In the most recent CNN poll, Republicans and Republican-leaning independents make up a solid majority of the relatively small bloc of US adults still entirely unvaccinated against Covid. Other polling, including surveys from the Kaiser Family Foundation, has found similar results.

While Republicans are generally opposed to vaccine mandates, most are, themselves, at least partially vaccinated. A 65% majority of Republicans and Republican-leaning independents report having received at least one dose of a Covid vaccine, according to CNN's latest polling. (By contrast, only about one-quarter see vaccination requirements as an acceptable way to increase the vaccination rate.)

There are notable differences between vaccinated and unvaccinated Republicans.

According to the Kaiser Family Foundation's October data, unvaccinated Republicans are younger, less likely to be college-educated, more likely to identify as conservative and disproportionately likely to live in rural areas. They were also less concerned about the pandemic: 88% said the seriousness of the coronavirus had been generally exaggerated, compared with 54% of vaccinated Republicans and just 8% of vaccinated Democrats who said the same.

A 62% majority of unvaccinated Republicans said they were "not at all worried" about getting sick from Covid-19, compared with 42% of vaccinated Republicans and 16% of vaccinated Democrats.

Trying to ask people what will -- or won't -- change their minds is a notoriously difficult undertaking. But there are some reasons to be a little skeptical about the extent to which Trump's statements will sway the most vaccine-resistant part of his base, even if he continues to publicly press the shots.

Back in March, as coronavirus vaccines were first made available, a CBS News poll conducted with YouGov tried an experiment to gauge how much influence Trump or President Joe Biden might have on the vaccine-hesitant.

First, they asked Americans about their likelihood of getting vaccinated. Several days later, they followed up again, but first informed some respondents that either Biden or Trump had endorsed the vaccine. Hearing about Trump, they found, did increase some Republicans' willingness to get vaccinated. But the effect came among those who had previously been on the fence; those who were outright resistant didn't budge.

A lot, of course, has changed since March. But as vaccination rates have increased, with initially hesitant Americans largely deciding in favor of getting the shot, the small share who say definitively that they won't hasn't dwindled. In the most recent Kaiser Family Foundation poll, some unvaccinated adults said they could imagine what might convince them -- if they were required to be vaccinated for work, or a doctor advised them to get the shot. About half, though, said that nothing would change their minds.