WASHINGTON — Young adults in Generation Z are refusing the COVID-19 shot at a higher rate than other age groups, a development that many public health experts and White House officials worry could prolong the virus’s spread and lead to dangerous new mutations.

“For young people who may think this doesn’t affect you, listen up, please. This virus, even a mild case, can be with you for months. It will impact on your social life,” President Joe Biden said at the White House on Wednesday.

Some public health experts warn that young adults’ decisions to shun the shot could have big consequences.

“I think our best bet to get closer to herd immunity, if not get there, is to pick up young people,” said Arthur Caplan, a professor of bioethics at New York University Langone Medical Center. “They can make a real dent when the remaining adults are still sort of hardcore vaccine-hesitant.”

The more people who refuse the vaccine, the more chances the virus has to mutate. American Public Health Association Executive Director Georges Benjamin said he is concerned the virus will mutate rapidly within unvaccinated, young and healthy people and create a new strain that is resistant to the COVID-19 vaccines on the market.

“The best way to think about them is little brushfires, little outbreaks,” Benjamin said. “We’re running the risk of starting this thing all over again.”

The young and healthy were not prioritized in the early days of the COVID-19 vaccination effort when much of the public health messaging focused on protecting the elderly and the frail.

When Gen Z adults who are 18 to 24 became eligible to get vaccinated, many didn’t see a need to rush. COVID-19 case numbers are falling, mask restrictions are disappearing and life has, in many ways, started returning to normal.

“The argument that this is protecting grandma doesn’t work any more because grandma’s already vaccinated,” Benjamin said.

Unlike other age groups, Gen Z vaccine hesitancy increased over time, polling shows.

Twenty-six percent of Gen Z adults say they are not vaccinated and have no plans to get the shot, according to a March 2021 poll from NBCLX and Morning Consult. That’s up from March 2020 when the same polling organization found just 5% of Gen Z adults said they would not get vaccinated for COVID-19.

Similarly, a recent STAT-Harris poll found that over half of Gen Z adults said they were not in any hurry to get the vaccine. This age group has a variety

This age group has a variety of reasons for not getting the shot. Some fell prey to misinformation on social media about negative side effects, such as unfounded rumors about the shot causing fertility issues.

Caplan said he likes to remind vaccine-hesitant people that vaccine side effects usually show up within a year and a half, and scientists have already looked for all these outcomes since trials began in March 2020. But contracting the virus can lead to serious issues down the line.

Some who have already had a mild case of the virus aren’t worried about contracting it again or believe they already have immunity. And others feel they can wait for a shot since many young and healthy people don’t contract severe disease if they get the virus.

The Biden administration is trying to nudge this group to get vaccinated with promotions, gimmicks and vaccine challenges.

On Wednesday, the White House and the Department of Education announced a COVID-19 College Vaccine Challenge to bring shots to universities. The administration is also encouraging students to participate in the COVID-19 Community Corps.

Biden and National Institute of Allergy and Infectious Diseases Director Anthony Fauci collaborated with You-Tube stars, including Manny MUA and Jackie Aina, to get out their vaccine messaging. In the somewhat campy videos, the president rotates between questions about COVID-19 vaccine development and his top desert island skin care product.

The administration is also reaching out to young people via dating apps, such as Hinge and Tinder. Vaccinated individuals can earn badges on their profiles and “super likes,” which can help them link up with vaccinated potential partners.

But this may not be enough. Jordan Tralins, a Cornell University rising junior, says much of the pro-vaccine messaging isn’t aimed at her generation. Most of her friends get their news from TikTok and Instagram, and much of the vaccine information on her feed was questionable at best. So she and a classmate founded the Covid Campus Coalition, a student-led organization that shares infographics and TikToks promoting information about COVID-19 vaccines. So far, the coalition has chapters in over 25 college campuses across the country, and Tralins plans to keep growing.

“I recognized at the start of the vaccination process that it’s just kind of a lack of presence in platforms where you know Gen Z and younger individuals spend their time looking,” Tralins said.

Though students at her university have been receptive to vaccination, that’s not the case for all colleges participating in the Covid Campus Coalition, she noted. Some larger universities in the South are having a more difficult time convincing students to get vaccinated.

Young adults “felt pretty invincible. They felt like if they got COVID, it wouldn’t be a big deal, so what’s the point of getting the vaccine?” Tralins said.

Lisa Costello, a West Virginia University assistant professor of general pediatrics, said she’s noticed that young adults and teens she works with are more likely to trust one another than the government. That’s why social media campaigns and peer-to-peer messaging can be effective.

“It’s also important in this group that we help this age group see the benefits of vaccination over the harm that COVID may pose to them,” Costello said.

Young adults ages 18 to 29 currently make up 22.5% of all COVID-19 cases in the U.S., more than any other age group and disproportionately higher than their share of the population, according to the latest Centers for Disease Control and Prevention data. Despite being such a high percentage of cases, they only make up 0.5% of virus deaths. The CDC doesn’t measure cases or deaths for adults ages 18 to 24.

Although people in Gen Z are much less likely to die of the virus, they could still spread it to others who are more vulnerable or suffer long-term health effects if they get COVID-19.

Despite the concerns, Amesh Adalja, a John Hopkins Center for Health Security senior scholar, is not overly worried about the low vaccination uptake among young adults in Gen Z. He hopes this age group will reach population-level immunity via a combination of vaccinations and natural infection, and virus spread in this relatively lowrisk age group will become endemic and seasonal.

“It would be much more worrisome if there was a group of 65-year-olds that were reluctant if instead of Gen Z, if it was the Greatest Generation or something,” Adalja said.

“We’re going to have to sort of recalibrate how we think about COVID-19 because it’s something that is not going away,” he added.