Coronavirus: Infected kids have massive amounts of viral RNA compared to adults - study

Moves to open schools overseas on the basis that children are less likely to catch or spread COVID-19 are flawed, a new study suggests.

"They don't transmit very easily," US President Donald Trump recently said. "They don't catch it easily, they don't bring it home easily, and if they do catch it, they get better fast."

While it so far appears true that children are less likely to fall seriously ill or die from COVID-19, with previous studies suggesting they're less likely to spread it than adults, new research in the US has found otherwise.

"Early reports did not find strong evidence of children as major contributors to SARS-CoV-2 spread, but school closures early in pandemic responses thwarted larger-scale investigations of schools as a source of community transmission," the new study, published in journal JAMA Pediatrics, reads.

Researchers in Chicago took swabs from 145 COVID-19 patients aged one-month to 65 years old in March and April as the pandemic took hold in the US. While older children - aged five to 17 - had similar levels of the virus' RNA in their upper respiratory tracts as adults, young children had between 10 and 100 times more.

"Our analyses suggest children younger than five years with mild to moderate COVID-19 have high amounts of SARS-CoV-2 viral RNA in their nasopharynx compared with older children and adults," researchers said. SARS-CoV-2 is the name of the virus which causes the wide-ranging symptoms collectively known as COVID-19. 

While the presence of more viral RNA doesn't necessarily mean they're more infectious, prior studies have found this to generally be the case.

"Thus, young children can potentially be important drivers of SARS-CoV-2 spread in the general population, as has been demonstrated with respiratory syncytial virus, where children with high viral loads are more likely to transmit.

"Behavioral habits of young children and close quarters in school and day care settings raise concern for SARS-CoV-2 amplification in this population as public health restrictions are eased. In addition to public health implications, this population will be important for targeting immunisation efforts as SARS-CoV-2 vaccines become available."

COVID-19 becomes more deadly the older the patient. Data collected early in the pandemic suggested the mortality rate for people 80 and over could be as high as 15 to 20 percent, but since then it's emerged the virus can spread asymptomatically - so it remains unclear how many people might have been infected without even realising they had it.

There have been widespread reports of a strange inflammatory syndrome linked to the virus in children, although deaths among young people due to COVID-19 are rare.

COVID-19 is unusual amongst infectious diseases for not having a higher mortality rate amongst very young children. Researchers in Switzerland in June suggested it could be the quality of their blood vessels, which are yet to be ravaged with age.