The findings, published by health care think tank Kaiser Family Foundation (KFF) on Wednesday, highlight the significant challenges that lie ahead as some of the progress the U.S. has made in stemming the coronavirus over the past year is reversed by the COVID Delta variant. Case counts are spiking nationwide, especially in regions with low vaccination rates.

The vaccine skepticism follows sociopolitical and demographic lines. Women, for instance, are more likely to say they have gotten a shot. But political ideology is the dominant factor in explaining who is and isn’t getting a vaccine, the survey found.

“The gender gap in vaccine uptake that emerged last month is still present with women still eight percentage points more likely to report being vaccinated than men (71% vs. 63%), and a larger share of men saying they will ‘definitely not’ get the vaccine (18% vs. 10%),” the survey’s authors said. “Yet, this is still largely attributed to the differences in partisan identification between men and women, with larger shares of men than women identifying as Republicans or Republican-leaning independents.”

More than 165 million Americans are fully vaccinated against COVID, or nearly 50% of Americans—both adults and youth, according to the Centers for Disease Control. Meanwhile, more than 192 million have received at least one dose, or 58% of the public.

On Monday, the Biden administration said that 70% of U.S. adults have had at least one dose. But that still leaves nearly 52 million adults without a single COVID shot.

Among those who haven’t received a vaccine, there are various degrees of enthusiasm for getting one. In fact, the share of those who will “likely” get a vaccine is evenly split among those who are “very likely” to get a COVID jab and those who are just “somewhat likely.”

Kaiser Family Foundation

Those who are most skeptical of COVID vaccines believe they do them more harm than contracting COVID-19 itself, a claim that has been debunked by clinical trials of authorized COVID vaccines that show how effective they are in preventing severe coronavirus illness, hospitalizations, and death. Fifty-three percent of the unvaccinated surveyed by KFF said they believed the vaccine may be more dangerous than the disease. More than half of that group also thinks the pandemic has been blown out of proportion by the media and don’t believe that the Pfizer, Moderna, or Johnson & Johnson vaccines are as effective as reported in the news and by public health officials.

On the flip side, 88% of those who have received shots say COVID-19 is the bigger health risk. Convincing the skeptics to shift their thinking along those lines will be a major challenge, as the study findings show.