Sweden kept preschools, primary and lower secondary schools open during the spring of 2020. So far, little research has been done on the risk of children being seriously affected by COVID-19 when the schools were open. A study from Karolinska Institutet in Sweden has now shown that one child in 130,000 was treated in an intensive care unit on account of COVID-19 during March-June. The study has been published in New England Journal of Medicine.

So far, more than 80 million people have become ill with COVID-19 and globally, almost two million people have died from the disease. Many countries have closed down parts of society in order to reduce the spread of infection. One such measure has been to close schools.

According to the United Nations body UNESCO, schools in 195 countries have been fully or partially closed. Even now, hundreds of millions of children around the globe are unable to go to their schools because of enforced closures.

In Sweden, distance learning was put in place for upper secondary schools but not for preschools, primary or lower secondary schools which instead remained open.

So far, there have been no data on how open schools affect the risk of children being seriously affected by COVID-19. Because of that, researchers at Karolinska Institutet have conducted a registry study to find out how many children aged 1-16 years were treated in an intensive care unit for COVID-19 or for multi-inflammatory syndrome (MIS-C) which has been linked to COVID-19.

Between 1 March and 30 June 2020, 15 children with COVID-19 or MIS-C were treated in intensive care units in Sweden.

“That is the equivalent of 0.77 intensive care patients per 100,000 children in that age group. Four of the children had underlying diseases. None of the children died within two months after their period of intensive care,” says Jonas F. Ludvigsson, paediatrician at Örebro University Hospital, Professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, and the first author of the study.

Seven of the 15 children had MIS-C. Four children needed invasive mechanical ventilation. The most common length of time in an intensive care unit was four days.

“It is very gratifying that serious COVID-19, defined here as needing treatment in an intensive care unit, is so rare among children despite schools being open during the pandemic. The next step will be to follow up the children who were treated in an intensive care unit for COVID-19 to see if they have recovered fully. My gut feeling is that children who have been seriously ill because of MIS-C seem to recover fully eventually,” says Jonas F. Ludvigsson.

This study was made possible through collaboration between the Swedish Intensive Care Registry and the Swedish Paediatric Rheumatology Registry. Jonas F. Ludvigsson is managing an unrelated study on behalf of the Swedish Quality Registry for IBD, SWIBREG. There are no other reported conflicts of interests.