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  • Mild COVID-19 disease and few long-term effects among children

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Mild COVID-19 disease and few long-term effects among children

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COVID-19 is generally not dangerous for children and adolescents. Infected children and adolescents most often have very mild symptoms of COVID-19, and 20-30 % have no symptoms at all. Those who experience mild symptoms may have a sore throat, cough, headache, and lethargy, and some may experience body aches and fever.

COVID-19 is generally not dangerous for children and adolescents. Infected children and adolescents most often have very mild symptoms of COVID-19, and 20-30 % have no symptoms at all. Those who experience mild symptoms may have a sore throat, cough, headache, and lethargy, and some may experience body aches and fever.


Few children and adolescents become very ill and need to be admitted to hospital. It seems that long-term effects of COVID-19 are uncommon among children and adolescents.

Few children become seriously ill

Figures from Norway show that 0.4 % of those who are diagnosed with COVID-19 infection aged 0-17 years are admitted to hospital. The average time they are in hospital (in-patient) is 2 days, which indicates that most recover quickly. So far in Norway, about 140 children with COVID-19 have been admitted to hospital since the start of the pandemic. Children with underlying risk conditions are admitted to hospital somewhat more often, but do not have an increased risk of becoming infected. It is important to emphasise that even for those who have the most severe clinical picture, the inflammatory condition MISC which can occur 2-6 weeks after infection, there is successful treatment and a good prognosis.

Both Norwegian and international data show that children under the age of 1 year are most often admitted to hospital in the 0-17 year age group. This is also seen for other infections among children, as the youngest children tolerate both fever and respiratory tract symptoms less well than older children. In addition, there is a lower threshold for admitting the youngest children.

The youngest children can be protected against COVID-19 if the mother has been vaccinated during pregnancy, something the Norwegian Institute of Public Health now recommends. When pregnant women are vaccinated, antibodies are formed against the coronavirus that are transmitted to the foetus, protecting the baby from disease during the first months of life. This is also known from other vaccines given to pregnant women; that vaccination during pregnancy protects both the mother and the newborn baby.

Deaths among children due to COVID-19 disease are very rare.  In England, all deaths among children and adolescents in the first year of the pandemic were reviewed, and it was found that 25 deaths were caused by COVID-19. In 76 % of these cases, there was a serious underlying and life-limiting disease. They estimate that there are 2 deaths per million children and adolescents aged 0-17 years. In Norway, there have been two deaths in the age group 0-19 years so far.

The Norwegian Institute of Public Health's modelling for calculating the number of children and young people who may be admitted to hospital in the future is uncertain, but estimates are low. It is therefore not expected that many children and adolescents will become seriously ill from COVID-19 or that hospitalisation of children will threaten the capacity of the health services.

Among those who are not offered a vaccine, we must expect that there will be some infection throughout the autumn and winter. The consequences of infection in this age group are small; most have no symptoms or mild illness. For those under the age of 12, there is also no approved vaccine. There are no published results of studies related to vaccination of children under 12 years. Therefore, it will take a while until vaccines will be considered for them. This age group has a low disease burden and contributes relatively little to transmission.

Continued infection control measures in schools and childcare centres

It is important to emphasise that there will still be measures for infection control in schools and childcare centres. Measures are still being taken to limit transmission; firstly, people who have symptoms of a respiratory tract infection should not attend school or work, but stay at home and be tested. In addition, those who are diagnosed with COVID-19 are placed in isolation, and household members are quarantined. It is not a goal for all children to be infected.

“We still want to have some restriction on the infection, but we accept that some children will get COVID-19. This is an unfamiliar situation for many, because there have been so few children and adolescents who have been infected so far. We must constantly assess the proportionality of the measures; Strict measures for a disease that is not so serious for children and adolescents are not proportionate. The alternative to normalising everyday life as much as possible now and in the future is to continue with measures that strongly affect the children's lives. Here we also learn more and more about the negative effects of stringent measures for children,” says Greve-Isdahl. “I understand that parents can be worried, when the news has been full of COVID-19 for a year and a half. However, it is very important to emphasise that COVID-19 is not a serious infection for children, and that the few children who need hospitalisation receive good treatment and there is a good prognosis, even for the most serious disease in children: the inflammatory condition MIS-C,” says Greve-Isdahl

What do we know about long-term health effects of COVID-19?

Long-term health effects (sequelae) of COVID-19 (also referred to as long COVID) are not precisely defined. Various symptoms have been reported among adults such as loss of sense of smell, fatigue, shortness of breath or cognitive problems.

“Among children and young people, it seems long-term symptoms are less common after recovery from COVID-19,” says Greve-Isdahl.

In studies comparing symptoms among children who have had COVID-19 with children who have not had COVID-19, the majority have no symptoms after 4-12 weeks. Among those who have symptoms after infection, symptoms were also seen in the control group who did not have COVID-19.

 “This does not mean that children or adolescents will not develop long-term symptoms after infection, but it does not seem to be common among children and adolescents,” says Greve-Isdahl.

“It is also important to emphasise that we cannot directly translate knowledge about infection from adults to children; we know that the disease is very different in terms of symptoms, severity and risk of death. Children and adolescents have a good biological basis to cope with new viral infections,” she says.

The largest and most significant study is from the UK and was recently published in the journal Lancet Child and Adolescent Health. It examined 1734 children in two age groups (5-11 years and 12-17 years). 77 of the children (4.4%) had symptoms after 28 days, and only 25 (1.8%) had one or more symptoms after 56 days. 98.2% then had no symptoms, and more recovered as time went on.

“We would have liked even more and longer-term studies, but we are not at a disadvantage when it comes to knowledge, Greve-Isdahl concludes. “The knowledge we have does not give reason to believe that long-term effects after COVID-19 are a major threat to child and adolescent health.”