WASHINGTON (NEXSTAR) – Forty million Americans are now fully vaccinated against COVID-19.

However, in the race between vaccinations and variants, the nation’s top health experts warn many who are eligible still won’t give the vaccine a shot.

“We need to address them at the local level,” CDC Director Dr. Rochelle Walensky told the Senate Health Committee Thursday.

Walensky said resources from the latest relief bill will help state health departments with outreach, but there is still a laundry list of reasons why some remain hesitant.

“Is it because it’s not convenient? Is it because people are not deeming it safe? Is it because they felt like it happened too fast, or they’re worried about side effects?,” Walensky asked.

Sen. Bill Cassidy, R-LA, stressed there needs to be more focus on the group with the greatest hesitancy: Republicans in rural areas.

“For some reason when people speak about equity and the need for special outreach, those folks never come up,” Cassidy said.

While states continue to work on that messaging, GOP lawmakers continue to question the Biden administration’s message to migrants at the border.

“For some reason, the White House continues to let people in with this virus,” Sen. Tommy Tuberville, R-AL, said.

Tuberville and Sen. Roger Marshall, R-KS, said that policy doesn’t make sense.

“I can’t have Easter service worship together, but we’re gonna let people come across the border in mass numbers and just release them,” Marshall said. “Does that not seem hypocritical?”

“I think there are two different situations,” Walensky responded. “And we have to handle them in two different ways.”

Walensky said the CDC is working with Office of Refugee Resettlement to make sure children are screened and tested.