Why children are more immune to COVID-19?

COVID-19 has been with us for more than a year already. But do you remember how little we knew about it just one year ago? We didn’t know what this viral disease can do to children. It turned out, they are more immune to COVID-19 than adults are. But why? Scientists at the University of Melbourne say that it is because children’s innate immune system is quick to attack the virus.

Children’s bodies are able to react to COVID-19 infections quicker, removing viruses before they take hold and preventing more difficult symptoms. Image credit: HFCM Communicatie via Wikimedia (CC BY-SA 4.0)

As you may know, COVID-19 affects people differently. Not everyone is at the same risk of complications and death as others. While old people are in a particularly high risk group, children rarely get COVID-19 and even when they do complications are exceptionally rare. Dr Melanie Neeland, one of the authors of this new study, explained: “Children are less likely to become infected with the virus and up to a third are asymptomatic, which is strikingly different to the higher prevalence and severity observed in children for most other respiratory viruses”. But why is that so? Scientists decided to investigate how young immune systems manage to protect children from this pandemic disease.

Scientists took blood samples of 48 children and 70 adults across 28 Melbourne households infected with or exposed to the SARS-CoV-2 virus, which causes COVID-19 disease. Researchers analysed those samples, playing close attention to immune responses to infection. Scientists wanted to see what is the difference between adult and children COVID-19 response. They found that COVID-19 response in children was characterised by activation of neutrophils – white blood cells that are specialised in healing damaged tissues and resolving infections.

Children also more quickly reacted to COVID-19 infection with an increase in  monocytes – dendritic cells and natural killer cells from the blood. All in all this means that the immune system of children was more quick to react, dealing with the virus quickly and removing the infection before it was able to take hold. That is why serious COVID-19 infections are very rare among children. The same kind of responses were not seen in adults, which is why children are more commonly asymptomatic COVID-19 patients, experiencing no fever, loss of the sense of taste, headaches or other common COVID-19 symptoms. This information is very important in the context of COVID-19, but it is also useful for preparation for future pandemics.

COVID-19 pandemic is going to go away sometime soon. Not tomorrow, not the day after tomorrow, but someday not in such a distant future. However, we need to be prepared for future pandemics, which are inevitable. Understanding risk groups and effective prevention measures is important, because it will help us be more prepared and ready.

Source: University of Melbourne