LOS ANGELES -- Nearly 12.9 million children in the United States have tested positive for COVID-19 since the onset of the pandemic, according to the latest report by the American Academy of Pediatrics (AAP) and the Children's Hospital Association.

Over 114,000 of these cases have been added in the past 4 weeks. Since the first week of last September, there have been over 7.8 million additional child COVID-19 cases in the country, according to the report published late Monday.

Children represented 19 percent of all COVID-19 cases in the United States, according to the report.

Over 25,000 child COVID-19 cases were reported the past week ending April 7.

There is an urgent need to collect more age-specific data to assess the severity of illness related to new variants as well as potential longer-term effects, said the AAP.

"It is important to recognize there are immediate effects of the pandemic on children's health, but importantly we need to identify and address the long-lasting impacts on the physical, mental, and social well-being of this generation of children and youth," said the AAP.