Coronavirus in children: Could blood vessels explain the low number of complicated cases?

  • Little is known about how the new coronavirus specifically affects children
  • Recent research looked at adult Covid-19 patients' arteries
  • Researchers believe differences in blood vessels between adults and children may help shed light  

Children have mostly had mild cases of the coronavirus – the elderly and those who have pre-existing chronic conditions and weakened immune systems seem to have more severe cases of Covid-19. Scientists have been trying to unravel this mystery for months.

One of the proposed reasons is that with age, comes a deterioration of the immune system, and with that, as a previous Health24 article explains, chronic diseases such as high blood pressure and diabetes, ultimately make it harder to fight off infections.

A recent study, published in The Lancet, states that increasing evidence points to the difference in the condition of blood vessels between adults and children. The study was carried out by 10 researchers who studied the arteries of adults infected with Covid-19, and said that this may shed further light on why children are at extremely low risk of becoming ill when contracting the virus.

Clotting and a malfunctioning endothelium

The team of researchers looked at three Covid-19 adult patients, aged 71, 58 and 69, two of whom died. They found that the virus infected one of the patients' endothelium, and led to inflammation and signs of clotting. Endothelial cells participate in several physiological functions, and are known for acting as a barrier between blood and body tissue and work to prevent blood clotting. 

According to a 2012 study published on IntechOpen, ageing influences endothelial cells and cause a progressive deterioration of their function, which may explain why children are more protected from serious effects of Covid-19, such as stroke.

Lead researcher of the study, Frank Ruschitzka, a cardiologist at the University Hospital Zurich in Switzerland told Nature that many adults who present with severe Covid-19, experience clotting in their blood vessels, which can lead to heart attacks or strokes, and explained that the clotting appeared to be linked to a malfunctioning endothelium.

The role of blood clot formation

Blood clots usually form when triggered by a cut or injury, for example, and work to stop the bleeding. However, they can also form due to a damaged endothelium. Through their study results, the research team suggests that issues with the endothelium have commonly presented in many severe or fatal adult Covid-19 cases.

For people with conditions that compromise the endothelium, such as diabetes and hypertension, this may possibly explain why they are also at a high risk of experiencing severe Covid-19, Marcel Levi, a haematologist at University College Hospital told Nature.

However, because the recent study involved just three adults, further investigation into these complications is needed, Ruschitzka said.

Children and 'healthy blood vessels'

Paul Monagle, paediatric haematologist at the Melbourne Children's Campus told Nature that scientists believe children’s blood vessels are better able to withstand a viral attack than adults, and added that the fact that case studies show few children with Covid-19 present with excessive clotting and damaged vessels may support this.

However, Monagle is trying to determine what exactly occurs when SARS-CoV-2 enters the endothelial cells, and has, therefore, launched two experiments to see if there may be something "protective" about children's blood vessels that causes an unlikelihood of excess clot production in response to a viral infection.

Lung damage in paediatric Covid-19

Another recent study, reported by Health24, involved a case investigation published in the American Journal of Roentgenology (AJR) that showed that most (77% of patients studied) young Covid-19 patients have negative chest CT findings. Simply put, their lungs present as normal and no damage is found.

Professor Eugene Weinberg, a paediatric allergologist who was on the News24 Frontline panel discussion on Wednesday, also stressed that in children who contract the virus, only 1% have severe symptoms and the rest mild or no symptoms.

Statistics further indicate that in South Africa, out of a total of 1 210 deaths (recorded on 10 June), only six occurred in people under the age of 20.

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