AP Photo/Hans Pennink, File

FILE - In this July 27, 2020, file photo, Nurse Kathe Olmstead, right, gives a volunteer an injection as a study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway in Binghamton, N.Y. 

WASHINGTON (AP) — As states frantically prepare to begin months of vaccinations that could end the pandemic, a new poll finds only about half of Americans are ready to roll up their sleeves when their turn comes.

The survey from The Associated Press-NORC Center for Public Affairs Research shows about a quarter of U.S. adults aren’t sure if they want to get vaccinated against the coronavirus. Roughly another quarter say they won’t.

Many on the fence have safety concerns and want to watch how the initial rollout fares — skepticism that could hinder the campaign against the scourge that has killed nearly 290,000 Americans. Experts estimate at least 70% of the U.S. population needs to be vaccinated to achieve herd immunity, or the point at which enough people are protected that the virus can be held in check.

“Trepidation is a good word. I have a little bit of trepidation towards it,” said Kevin Buck, a 53-year-old former Marine from Eureka, California.

Buck said that he and his family probably will get vaccinated eventually, if initial shots go well.

“I think a lot of people are not sure what to believe, and I’m one of them,” he said.

Amid a frightening surge in COVID-19 that promises a bleak winter across the country, the challenge for health authorities is to figure out what it will take to make people trust the shots that Dr. Anthony Fauci, the top U.S. infectious-disease expert, calls the light at the end of the tunnel.

“If Dr. Fauci says it’s good, I will do it,” said Mary Lang, 71, of Fremont, California. She added: “Hopefully if enough of us get the vaccine, we can make this virus go away.”

Early data suggests the two U.S. frontrunners — one vaccine made by Pfizer and BioNTech and another by Moderna and the National Institutes of Health — offer strong protection. The Food and Drug Administration is poring over study results to be sure the shots are safe before deciding in the coming days whether to allow mass vaccinations, as Britain began doing with Pfizer’s shots on Tuesday.

Despite the hopeful news, feelings haven’t changed much from an AP-NORC poll in May, before it was clear a vaccine would pan out.

In the survey of 1,117 American adults conducted Dec. 3-7, about 3 in 10 said they are very or extremely confident that the first available vaccines will have been properly tested for safety and effectiveness. About an equal number said they are not confident. The rest fell somewhere in the middle.

About 7 in 10 of those who said they won’t get vaccinated are concerned about side effects. Pfizer and Moderna say testing has uncovered no serious ones so far. As with many vaccines, recipients may experience fever, fatigue or sore arms from the injection, signs the immune system is revving up.

But other risks might not crop up until vaccines are more widely used. British health authorities are examining two possible allergic reactions on the first day the country began mass vaccinations with the Pfizer shot.

Among Americans who won’t get vaccinated, the poll found 43% are concerned the vaccine itself could infect them — something that’s scientifically impossible, since the shots don’t contain any virus.

Protecting their family, their community and their own health are chief drivers for people who want the vaccine. Roughly three-quarters said life won’t go back to normal until enough of the country is vaccinated.

“Even if it helps a little bit, I’d take it,” said Ralph Martinez, 67, who manages a grocery store in Dallas. “I honestly think they wouldn’t put something out there that would hurt us.”

Over the summer, about a third of Martinez’s employees were out with COVID-19. He wears a mask daily but worries about the constant public contact and is concerned that his 87-year-old mother is similarly exposed running her business.

COVID-19 has killed or hospitalized Black, Hispanic and Native Americans at far higher rates than white Americans. Yet 53% of white Americans said they will get vaccinated, compared with 24% of Black Americans and 34% of Hispanics like Martinez.

Because of insufficient sample size, the survey could not analyze results among Native Americans or other racial and ethnic groups that make up a smaller proportion of the U.S. population.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.