Nearly 72,000 children in the U.S. tested positive for COVID-19 last week, a massive jump from the approximately 39,000 cases among kids one week earlier, according to a new report from the American Academy of Pediatrics and the Children’s Hospital Association.

Children represented 19% of all COVID-19 cases for the week ending July 29.

Severe illness due to COVID-19 remains "uncommon" among children, the two organizations wrote in the report. According to the nearly two dozen states that reported pediatric hospitalizations, 0.1% to 1.9% of all child COVID-19 cases resulted in hospitalization.

However, the two organizations warned that there is an urgent need to collect more data on long-term impacts of the pandemic on children, "including ways the virus may harm the long-term physical health of infected children, as well as its emotional and mental health effects."

-ABC News’ Arielle Mitropoulos

According to federal data, nearly 56,000 patients are now hospitalized with COVID-19 across the U.S., marking the highest number of patients receiving care since February.

Ninety-one percent of Americans are now living in high (a seven-day new case rate ≥100) or substantial (a seven-day new case rate between 50-99.99) community transmission in the last week.

Seven states -- Alabama, Arkansas, Arizona, Delaware, Florida, Louisiana and South Carolina -- have high or substantial community transmission in every county.

Louisiana, Arkansas, Florida, Missouri, and Alabama currently have the nation's highest case rates, followed by Mississippi, Texas, and Oklahoma.

-ABC News’ Arielle Mitropoulos

In Texas, the demand for vaccines is skyrocketing. The number of daily doses has jumped from about 44,000 (just after the 4th of July) to 73,000 as of Monday, said Chris Van Duesen, spokesperson for the state’s Department of State Health Services.

National Institutes of Health director Francis Collins told CNN Tuesday the data is "tipping" toward showing how the delta variant is more serious for children than past variants.

Collins listed studies from Singapore, Scotland and Canada that "certainly tilts the balance in that direction" but made clear that more data is needed.

Collins also added that part of the reason the U.S. is seeing more children in hospitals is because they're part of the unvaccinated population and he doesn't want to "overstate the confidence."

-ABC News’ Cheyenne Haslett

In Louisiana, which has the nation's highest case rate per 100,000 residents, COVID-19 hospitalizations are reaching peak levels, with more than 1,700 patients now receiving care.

"We're seeing people that are way too young to be so sick," David Wrightson, a respiratory therapist and ECMO (extracorporeal membrane oxygenation) specialist for the Willis-Knighton Health System in Shreveport, Louisiana, told ABC News. "We see families destroyed. We see children without one or more parent because of this virus. We see a new mom who will never go home to see her newborn, will never see her child grow up."

He went on, "When you see someone that's 30 years old with no medical problems at all, nobody knew anything was wrong, and we have this person literally on death's doorstep, doing everything in our power to turn them around and return them to their family. The vaccine is something worth getting."

More people need to see and understand the reality of this disease, he said.

"I wish I could show them a few steps in our day to see what we see and to see what we have to do, and to go home at night and, and have nightmares about those things, and sometimes cry yourself to sleep," he said.

-ABC News’ Erica Baumgart and Arielle Mitropoulos