- Researchers have found new evidence to explain why children aren't as severely affected by Covid-19
- According to their findings, the answer lies in the antibodies produced in children in response to SARS-CoV-2 infection
- This results in the virus being cleared more easily from their systems
The new coronavirus spares most children, and researchers of a study may know why. According to their findings, children and adults produce different types and amounts of antibodies in response to infection.
The researchers from Columbia University Vagelos College of Physicians and Surgeons wrote that the differences in antibodies suggest the period of infection, as well as the immune response, is distinct in children. They also found that most children easily clear the virus from their bodies.
"Our study provides an in-depth examination of SARS-CoV-2 antibodies in kids, revealing a stark contrast with adults," Dr Donna Farber, Columbia University immunologist and co-author of the study, said in a news release.
Dr Matteo Porotto, associate professor of viral molecular pathogenesis in Columbia's Department of Pediatrics, led the study with Farber and commented that because children may clear the virus more efficiently than adults, they may not need a strong antibody immune response to get rid of it.
They also wrote that, since children's cells express fewer proteins the virus needs to infect human cells, it could explain why the virus is less able to infect children's cells compared to adults.
Their findings were published in the journal Nature Immunology.
Children and T cells
Since the start of the pandemic, children have been largely found to cope well with the virus, compared to the elderly and those with comorbidities.
Farber explained that children have a lot of “naive T cells”.
T cells play a central role in orchestrating the immune response, in that they find infected cells in the human body and destroy them, Professor Thomas Scriba, Deputy Director of Immunology and Laboratory Director at the University of Cape Town, previously told Health24.
These cells, Farber added, are able to recognise all sorts of new pathogens. In comparison, older people depend more on their immunological memories: “We're not as able to respond to a new pathogen like children can," she said.
Children found to produce fewer SARS-CoV-2 neutralising antibodies
A Health24 article explains that antibodies perform their role by binding to specific parts of a virus, and neutralise the virus’s damaging effects (also known as “neutralising antibodies”).
The study showed that, compared to adults, children produced fewer neutralising antibodies against the virus's spike protein (which mediates viral entry into human cells) than all the adults analysed in the study, including young adults in their 20s.
The sickest adults, the team found, had the most neutralising activity.
Farber explained that this finding likely reflects the amount of time SARS-CoV-2 is present in the sickest patients.
"There is a connection between the magnitude of your immune response and the magnitude of the infection: the more severe the infection, the more robust the immune response, because you need to have more immune cells and immune reactions to clear a higher dose of a pathogen," she said.
Children infectious for shorter period: explained
Farber said that infection doesn't spread a lot and doesn't kill a lot of their cells in children, which can be explained by children producing very few antibodies against a viral protein that is only visible to the immune system after the virus infects cells, with Porotto commenting:
"Because children clear the natural virus rapidly, they do not have a widespread infection and they do not need a strong antibody response.”
"Current studies in other countries indicate that younger school-age children are not vectors for the new coronavirus, so our data are consistent with those findings," Farber said.
However, the researchers stated that they did not measure viral load in the children. They also noted that it's still unclear how exactly children are able to clear the virus more easily than adults, and what the adult immune system lacks.
Findings good news for children and potential Covid-19 vaccine
According to the authors, children should respond favourably to a Covid-19 vaccine, if one becomes available.
"Even though children don't produce neutralising antibodies in response to a natural infection with SARS-CoV-2, vaccines are designed to generate a protective immune response in the absence of an infection," Farber said.
"Children respond very well to vaccines, and I think they will develop good neutralising antibody responses to a SARS-CoV-2 vaccine, and they'll probably be better protected than the adults."
However, since very few active vaccine studies are enrolling children, the researchers indicated that this data will be required to understand how well the vaccines work in children.
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