So, what is protecting children?
“No one has a good answer to that question yet,” says Iwasaki. But she and other experts suspect it may be down to the unique way children’s immune systems respond to these viruses.
A common complication of covid-19, SARS and MERS in adults is acute respiratory distress syndrome, where the immune response against the coronavirus becomes overzealous and causes life-threatening damage to the lungs.
The resulting leakage of fluid and immune cells into the lungs causes big problems, says Chris van Tulleken at University College London. Even if those immune responses are trying to help by attacking the virus, they can end up blocking oxygen uptake in the lungs, he says.
Because children’s immune systems are still developing, one suggestion is that they are shielded from this type of dangerous immune response – called a cytokine storm – when they get covid-19 or similar diseases. During the SARS outbreak, two studies found children produced relatively low levels of inflammation-driving cytokines, which may have been what protected their lungs from serious damage.
That doesn’t explain why children’s immune systems react differently to coronaviruses compared with flu. It might be due to differences in the type of cytokine response produced against each virus, says Iwasaki.
Children may also be benefiting from their lack of past exposure to coronaviruses generally. Because they have lived longer, adults are more likely than children to have encountered other coronaviruses in their lives, such as those that cause coughs and cold, and to already have antibodies against these milder viruses.
There is a suggestion that these existing antibodies could actually leave adults worse off, because they aren’t exactly matched to the new coronavirus. “Sometimes unmatched antibodies can be more harmful than good,” says Wendy Barclay at Imperial College London.
Read more:
https://www.newscientist.com/article/2237259-why-dont-children-seem-to-get-very-ill-from-the-coronavirus/#ixzz6GqjOwvL1
