More than half a million children in the US have tested positive for the novel coronavirus since the onset of the pandemic earlier this year, according to a new report.

The report by the American Academy of Paediatrics and the Children's Hospital Association said that while children represented only 9.8 per cent of all cases in states reporting cases by age, a total of 513,415 child Covid-19 cases have been reported, reports Xinhua news agency.

The overall rate is 680 cases per 100,000 children in the population.

According to the report, 70,630 new child cases were reported from August 20 to September 3, a 16 per cent increase in over two weeks.

Children made up between 4 and 14.3 per cent of total state tests, and between 3 and 17.3 per cent of children tested were tested positive, according to the report.

Children were 0.7 to 3.7 per cent of total reported hospitalizations, and 0 to 0.3 per cent of all Covid-19 deaths, said the report.

"At this time, it appears that severe illness due to Covid-19 is rare among children. However, states should continue to provide detailed reports on cases, testing, hospitalizations, and mortality by age and race/ethnicity so that the effects of coronavirus on children's health can be documented and monitored," the report added.

The US continues to be the worst-hit country in the world by the coronavirus pandemic.

As of Thursday, the number of cases increased to 6,359,313, while the death toll stood at 190,796, according to the Johns Hopkins University.