Children appear to be less likely than adults to acquire the SARS-CoV-2 virus – and the virus looks different in children compared to how it manifests in adults.
This was the overriding viewpoint of a webinar entitled Covid-Kids, which was held during the Faculty of Medicine and Health Sciences' (FMHS) Annual Academic Day.
A number of studies which looked at contact tracing had shown that the secondary infection rate in children was significantly lower compared to that of adults, “so they seem less likely to get infected by contacts," said Dr Andrew Redfern of the Paediatric Emergency and Ambulatory Department at Tygerberg Hospital and the FMHS's Department of Paediatrics and Child Health.
Redfern added that the overall case incidence worldwide also demonstrated that children only represent between 1% and 3% percent of cases.
Redfern shared the virtual platform with Professor Helena Rabie and Dr Marieke van der Zalm, both from the department of Paediatrics and Child Health.
Redfern said older children are at greater risk of infection, while younger children are at greater risk of severe disease. Nevertheless, he said, children are very unlikely to die from the virus, and young children are not super spreaders of the virus.
He cited a case series of 100 children who presented to an emergency department in Italy earlier this year with confirmed SARS-CoV-2 infection, where about 20% were asymptomatic and the vast majority of the cases had mild to moderate or asymptomatic disease with only a handful needing oxygen support or intensive care. These figures mimicked the experience in South Africa “very closely."
Redfern said there are a number of theories on why children are less likely to get Covid-19 and why they are less severely affected by it.
Rabie, an investigator in the university's Covid-Kids project, described the newly-recognised syndrome known as Multisystem Inflammatory Syndrome (MIS-C) that has been identified in children and which seems to be related to Covid-19.
Also known as Paediatric Multisystem Inflammatory Syndrome (PIMS), the syndrome appears to be a delayed complication of the coronavirus infection, even though some children with MIS-C symptoms do not test positive for Covid-19. The syndrome has a range of symptoms that affect several organs and systems in the body and children often have symptoms which resemble toxic shock syndrome or Kawasaki disease in which blood vessels including the coronary arteries enlarge or form aneurysms. Other symptoms include severe blood clotting, gastrointestinal symptoms, kidney injury, neurologic symptoms and heart inflammation – and the symptoms can manifest in varied combinations.
Rabie, who assisted with Tygerberg Hospital's preparedness plan for Covid-19, as well as the screening and management of children with Covid-19 and MIS-C, said the MIS-C syndrome has been reported about two to four weeks after the onset of Covid-19 in children and adolescents.
Some researchers have cited the possibility that MIS-C is caused by a delayed “overdrive" immune response to the coronavirus which causes inflammation that damages organs. They also suspect that the antibodies children make to the virus are creating the immune reaction. Genetics could also play a role.
Rabie said as Covid-19 surges through the continent, more reports of MIS-C are expected in South Africa and sub-Saharan Africa. Health professionals in the region should be vigilant to the disease.
Van der Zalm said the aim of the Covid-Kids study was to define the clinical presentation, immune response and long-term consequences of respiratory virus infections (including SARS-CoV-2) in children presenting at Tygerberg Hospital during the pandemic.
She said it is very important to study differences in immune response between children and adults and children from different settings in order to understand Covid-19 disease.
Dr Van der Zalm confirmed that children seem to be relatively protected from severe Covid-19.
However little is known about lower- and middle-income countries and sub-Saharan Africa. “This is especially important as the under-five pneumonia mortality rate is significantly higher in our setting than in higher income countries. Risk factors associated with poor outcomes in pneumonia could potentially have an important impact on Covid-19 outcomes, such as HIV, TB and malnutrition."
The study – which, by the end of July involved 159 Covid-positive cases, of which 62 were admitted to hospital – is still ongoing.
Dr Van der Zalm said Covid-19 in children seems to be related to good short-term outcomes; however multiple readmissions had been noted, which needs to be followed up. The spectrum of the disease varies, she added. Younger children have the most severe respiratory disease and it is vital to watch out for new diagnoses in young children with Covid-19.