Professor Jonas Ludvigsson at the Karolinska Institute has reviewed 45 scientifically published studies on a total of 99,000 covid-19 patients.

In China, two percent of the children affected were in Italy, just over one percent and in the US five percent. Most of the affected children had fever and cough, but did not need intensive care. Only a 14-year-old in China and a 10-month-old infant with severe underlying disease died after being infected by the coronavirus.

It is also very rare for fetuses to be infected by their mothers, the research report shows.

Undeveloped enzyme can save children

There are two theories about why children rarely get sick in covid-19 and that they then usually get a mild variant.

- Children have a different immune system than adults, says Jonas Ludvigsson.

When the coronavirus is to attempt to gain attachment to a body, it binds to an enzyme found on the surface of, among other things, lung cells. This enzyme is called ACE2 and it is undeveloped in children. This could explain why children rarely become infected and do not become as ill.

Another explanation is that toddlers are often sniffed by other coronaviruses, ones that have been around for a long time and that only provide colds. Their immune system is therefore able to fight even the new corona virus better.

The new study also notes that in children with mild covid-19 symptoms, lung radiographs or computed tomography are probably not necessary.

Jonas Ludvigsson participates in the Science World special broadcast on the corona pandemic on Monday 30/3 at. 20.00 in SVT2.

Read the study here.