Washington, Over 4 million children in the US have tested positive for Covid-19 since the onset of the pandemic, according to a latest report of the American Academy of Pediatrics (AAP) and the Children's Hospital Association.

As of July 15, almost 4.09 million children have been infected with Covid-19. After decreases in weekly reported cases over the past couple of months, the country began to see increases in cases in July, according to the report.

Over 23,500 child cases were reported in the week ending July 15, according to the report. Children represented 14.2 per cent of all Covid-19 cases in the country, the Xinhua news agency reported.

Children accounted for 1.3 per cent to 3.6 per cent of total reported hospitalisations, and 0 to 0.26 per cent of all Covid-19 deaths, said the report.

"At this time, it still appears that severe illness due to Covid-19 is rare among children. However, there is an urgent need to collect more data on longer-term impacts of the pandemic on children, including ways the virus may harm the long-term physical health of infected children, as well as its emotional and mental health effects," the AAP said in the report.