Washington, Sep 28 : Over 14.7 million children in the US have tested positive for Covid-19 since the onset of the pandemic in early 2020, according to the latest report by the American Academy of Pediatrics (AAP) and the Children's Hospital Association. Over 289,000 of these cases have been added in the past four weeks, Xinhua news agency quoted the report published on Tuesday as saying. Approximately 6.85 million reported cases have been added in 2022, it added. For the week ending September 22, child Covid-19 cases accounted for 16.9 per cent of all infections reported in the US. But the reported cases are likely a "substantial undercount" of Covid-19 cases, according to the report. 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 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," the Academy added. /IANS