Washington, April 26 : Some 15.6 million children in the US are reported to have tested positive for Covid-19 since the onset of the pandemic in early 2020, according to a latest report. The report by the American Academy of Pediatrics (AAP) and the Children's Hospital Association revealed that about 9,000 child Covid-19 cases were recorded in the week ending April 20. Over the past 7 months, weekly reported child cases plateaued at an average of about 27,000 cases, while in the past four weeks the average reported weekly cases dropped further to about 11,000, Xinhua news agency quoted the report as saying. Reported cases are likely a "substantial undercount" of Covid-19 cases among children, it said. There is a 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 recognise there are immediate effects of the pandemic on children's health, but importantly there is the 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. The US remains the worst-hit country in the world with the highest number of both Covid-19 cases and deaths. As of Wednesday, the country's overall caseload and death toll stood at 106,585,478 and 1,159,417, respectively. /IANS