Los Angeles, April 20 : Over 12.9 million children in the US 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. Almost 116,000 of these cases have been added in the past four weeks. Since the first week of last September, there have been almost 7.9 million additional child Covid cases in the country, according to the data, Xinhua news agency reported. Children represented 19 per cent of all Covid cases in the US, the report showed. Over 33,000 child Covid cases were reported last week. 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. /IANS