Washington, Mar 29 (IANS): More than 15.5 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 new report.

The report by the American Academy of Pediatrics (AAP) and the Children's Hospital Association said that over 66,000 of these cases have been added in the past 4 weeks, Xinhua news agency reported.

Over 13,000 child Covid-19 cases were reported in the week ending March 23, it added.

Over the past six months, weekly reported child cases in the US have plateaued at an average of about 30,000 cases, according to the report.

Reported cases are likely a "substantial undercount" of Covid-19 cases among children, it noted.

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 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.

With the highest number of cases and fatalities, the US remains the worst-hit country by the Covid pandemic.

As of Wednesday morning, the country's caseload and death toll stood at 106,120,651 and 1,153,972, respectively.