(NewsNation Now) — A new study showed immunity from mRNA COVID-19 vaccines, like the ones Moderna and Pfizer produce, could last years.

“What we are seeing is that our immune system not only instructing our immune cells to generate a very good immune response, but also training those cells to perfect their ability to bind to the virus and block the virus,” Dr. Ali Ellebedy, a researcher behind the study, told NewsNationNow.com. “So this is good news.”

Ellebedy said if the virus did not mutate, immunity could last up to four years. However, with variants, a booster may still be necessary. You can watch his full interview in the player above.

Johns Hopkins in urging children and younger Americans need to be the center of the COVID-19 vaccination efforts in the U.S. as young adults are the group least likely to get a shot. This comes with deadlier variants, which one doctor called “COVID-19 on steroids,” spreading.

Andrew Leavitt, 29, is among the unsure. “It really is something that I debate pretty much weekly,” he said.

But some young Americans are not hesitating. Brodie Schulein-Rivkin, 18, is asthmatic and raced to get the vaccine.

“Ultimately, I just made sure I was safe, as well as everyone around me,” he said.

Right now, only Pfizer has emergency use authorization from the Food and Drug Administration for kids ages 12 to 15. Two vaccine trials are underway for ages 5 to 11.

A number of issues could slow the rollout for children, and some college students who can get shots are choosing not to.

The College World Series is over for North Carolina State, which was one win away from advancing to the championship game, because half of the team was out due to COVID-19 protocols.

The nation’s top doctors warn that young people are more vulnerable to variants, and to expect children in intensive care with COVID-19 this summer.

“We’re still going to see a lot of young adults get hospitalized and with long term, debilitating symptoms, what’s called long haul COVID, I think I’m very concerned about that,” Dr. Peter Hotez with Baylor College of Medicine said.

When NewsNation asked White House press secretary Jen Psaki for the administration’s message to parents, she said the process needs to play out.

“Obviously, we can’t get ahead of the FDA process for approving vaccines,” Psaki said. “I know parents like myself are eager to vaccinate their children. Some also will have many questions, as we have seen as the vaccine has become available for kids who are 12 and older.”