The head of the Centers for Disease Control and Prevention says she expects all students to be back in classrooms this fall.

In an Instagram Live interview with ABC News Chief Medical Correspondent Dr. Jennifer Ashton on Wednesday night, Dr. Rochelle Walensky said that conditions should improve enough between now and September for schools to retire remote learning, even if not all children will have had the opportunity to be vaccinated for COVID-19 by then.

“Not only will we have vaccines for people who are over the age of 12, but we have an extraordinary amount of testing that we can be doing,” Walensky said. “So I think with the combination of testing and vaccination for our older populations — and I really hope decreased number of cases — that we should anticipate come September 2021 that schools should be full-fledged in-person and all of our children back in the classroom. And I will really look forward to that.”

Many children nationwide have not seen the inside of a classroom in more than a year, doing their schooling online instead. President Joe Biden has set a goal for the majority of K-8 schools to reopen to full-time, in-person instruction by his 100th day in office, which will be at the end of the month.

A survey released by the Biden administration Wednesday found that 46% of public schools offered five days a week of in-person learning to all students in February, but just 34% of students were learning full-time in the classroom. 

In the United States, the only vaccine currently authorized for anyone under 18 years old is the one produced by Pfizer and BioNTech, which can be given to people 16 and older. 

Pfizer announced last month that clinical trial data shows its vaccine is safe and effective on 12- to 15-year-olds and is expected to soon request emergency use authorization from the Food and Drug Administration for that age group. 

The company also has started testing children ages 5 to 11 and plans to eventually work its way down to kids as young as 6 months.

Moderna has been testing its vaccine on 12- to 17-year-olds for months and announced last month it was expanding the trials to include children from 6 months to 11 years old. 

Johnson & Johnson said last month it likely will have a vaccine available to children younger than 18 by September.