(CNN) More than 121,000 child Covid-19 cases were reported in the US in the last week, according to a report from the American Academy of Pediatrics.
After declining in early summer, child cases have "steadily increased" since the beginning of July. From August 5 to August 12, a total of 121,427 child cases were reported, which the AAP calls "a continuing substantial increase."
Children represented 18% of the weekly reported cases.
Since the start of the pandemic, the AAP cites a cumulative total of 4,413,547 child cases reported, with children representing 14.4% of all cases.
Hospitalizations were reported by 23 states and New York City, and children ranged from 1.6% to 3.5% of their total hospitalizations. Of all child Covid-19 cases, 0.2% to 1.9% resulted in hospitalizations.
Children made up 0% to 0.25% of all Covid-19 deaths, which were reported in 43 states, New York City, Puerto Rico and Guam. No child deaths were reported by seven states, and 0% to 0.03% of all child Covid-19 cases in the states that reported resulted in death.
Covid-19 outbreaks have sent many students back into quarantine early in the new school year. One way to help students stay in classrooms is to have students -- particularly those who are not vaccinated -- wearing masks in school, health experts say.
"It shouldn't be for months. It shouldn't be forever. But right now, when people are coming back in, masking is a reasonable public health step," said Dr. Brett Giroir, former assistant secretary for health in the Trump administration.
"I support it and encourage parents to encourage their children to do it."
During this Delta variant surge, Covid-19 hospitalizations have soared among children. But the full extent of severe pediatric cases is unknown, said Giroir.
"Only 23 states and New York City actually report the number of children in hospitals," said Giroir, a pediatrician. He said Texas and Florida are among the states where the total number of child Covid-19 hospitalizations are unknown.
"Talking about flying blind, relative to children," Giroir said. "We need better data, and that's got to be the basis for action."