Two studies to be published Friday found fewer pediatric hospitalizations among children and communities with higher vaccination rates, the director of the U.S. Centers for Disease Control and Prevention said.

In one study, national data from August showed that children were nearly four times more likely to be hospitalized with COVID-19 in the states with the lowest vaccination rates when compared to states with the highest rates -- proof that "cocooning" children with vaccinated people keeps them safe, Dr. Rochelle Walensky said at a White House briefing Thursday.

The second study, which looked at hospitalizations rates in 12- to 17-year-olds across 14 states during July, found that adolescents who were unvaccinated were 10 times more likely to be hospitalized with COVID-19 than their fully vaccinated peers, Walensky said.

"Both studies, one thing is clear: cases, emergency room visits and hospitalizations are much lower among children and communities with higher vaccination rates," Walensky said. "We must come together to ensure that our children, indeed, our future, remain safe and healthy during this time."

-ABC News' Cheyenne Haslett

Eight school districts in Florida told the state's education commissioner that they would not reverse their mask requirements for students, clearing the way for the state to retaliate by withholding the salaries of school board members.

The eight districts -- Duval, Hillsborough, Indian River, Leon, Miami-Dade, Orange, Palm Beach and Sarasota -- each wrote a letter to Commissioner Richard Corcoran Wednesday saying they believed they were following state law and had no plans to stop requiring face coverings for students.

Corcoran had given each district until 5 p.m. Wednesday to reverse their mandates, threatening to recommend to the state education board that it withhold the salaries of board members if they did not change course.

The state education department announced Monday it would take such action against board members in Alachua and Broward counties over their school mask mandates.

On Friday, a Florida judge ruled that school boards can enact student mask mandates and ordered the state education department to stop enforcing a state rule requiring districts to allow parents to opt-out.

-ABC News' Will McDuffie

A new study out of Israel finds that certain cancer patients may see roughly equal vaccine protection as the general population.

Specifically, the study found a group of 154 cancer patients with solid tumors had an antibody response roughly equivalent to an equally-matched group of people without cancer six months after their second Pfizer shot. A subset of cancer patients undergoing chemotherapy, however, were the most likely to have antibody levels below a detectable threshold.

The study also found the Pfizer vaccine was safe for solid tumor cancer patients.

The study implies that not all cancer patients may need a third booster shot to achieve equal levels of protection as the general population. Presently in the U.S., the CDC and FDA say "moderate to severely" immune compromised people need a third shot -- which comprises roughly 3% of the U.S. population.

-- ABC News’ Sony Salzman

Liberty University switched all residential classes to be online and suspended indoor gatherings as the campus -- which does not require vaccinations for students or staff -- grapples with a new surge in COVID-19 cases.

The college reported 430 active cases of students with COVID-19 on Wednesday, according to ABC News’ local affiliate WSET-TV. This is more than the total number of cases at four neighboring Virginia colleges combined. The University of Virginia, Virginia Commonwealth University, Virginia Tech and James Madison University have reported a total of 125 students with active cases total.

The latter four universities require students to get the COVID-19 vaccine and wear masks, while Liberty does not require either.

A new study by the U.S. Centers for Disease Control and Prevention estimates that roughly 83% of blood donors in the nation have either been vaccinated against COVID-19 or were previously infected with the virus.

This, however, does not mean that more than 80% of Americans are immune from infection. That's because neither vaccination nor prior infection provides 100% protection -- antibodies are just one part of the overall immune response, and immunity wanes over time. The analysis also may overestimate the portion of people with antibodies because blood donors may be more likely to be vaccinated or have previously been infected.

The study, posted online Tuesday by JAMA Network Open, a monthly open access medical journal published by the American Medical Association, took a snapshot of the presence of antibodies from COVID-19 vaccination or prior infection in about 1.4 million donated blood samples from across the United States. The repeated cross-sectional analysis was conducted each month during July 2020 through May 2021, before delta became the predominant variant of the novel coronavirus in the U.S.

The study shows that the number of blood donors who tested positive for antibodies, indicating either vaccination or prior infection, has gone up over time, from 3.5% in July 2020 to 20.2% for infection-induced antibodies and 83.3% for both infection- and vaccine-induced antibodies in May 2021.

Being vaccinated offers better protection compared to prior infection, and it's recommended that people who have previously contracted COVID-19 should still get inoculated.

-ABC News' Katie Bosland and Sony Salzman