Children greet each other as they arrive at school in New York, the United States, March 7, 2022. (Xinhua/Wang Ying)

Since the first week of September, there have been over 7.7 million additional child COVID-19 cases, according to the AAP.

Almost 12.8 million children in the United States have tested positive for COVID-19 since the onset of the pandemic, according to the latest report published by the American Academy of Pediatrics (AAP) and the Children's Hospital Association.

A total of 12,752,636 child COVID-19 cases had been reported across the country as of March 10, and children represented 19 percent of all confirmed cases, according to the report.

Nearly 411,000 of these cases have been added in the past 4 weeks. About 42,000 child COVID-19 cases were reported in the past week, according to the report.

Since the first week of September, there have been over 7.7 million additional child COVID-19 cases, according to the AAP.

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 report.

"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 report.