The lining of children's noses is better at inhibiting SARS-CoV-2 infections than adult noses, a finding that may explain why a majority of kids were able to dodge the infectious virus.
The research, published in PLOS Biology, showed the virus replicated less efficiently in the children's nasal cells, as well as had a heightened antiviral response.
Dr. Kirsty Short from the University of Queensland in Australia said it might be one reason why children's immune responses have so far proven more effective at avoiding and fighting Covid-19.
"Children have a lower Covid-19 infection rate and milder symptoms than adults, but the reasons for this have been unknown," said Short from the varsity's School of Chemistry and Molecular Biosciences.
"We've shown the lining of children's noses has a more pro-inflammatory response to the ancestral SARS-CoV-2 than adult noses," she added.
The team exposed the samples of nasal lining cells from 23 healthy children and 15 healthy adults to SARS-CoV-2. Short said there were several theories behind kids' heightened antiviral response.
"It could be an adaptation to the increased threats of 'foreign invaders' such as viruses or bacteria observed in childhood," she said.
"It's also possible that increased exposure to these threats in childhood trains the nasal lining in children to mount a stronger pro-inflammatory response."
Alternatively, metabolic differences between children and adults could alter how virus-fighting genes express themselves.
"Further, the researchers found the Delta Covid-19 variant was significantly less likely to replicate in the nasal cells of children compared to adults. But the trend was markedly less pronounced in the case of Omicron.aceTaken together, it shows children's nasal lining supports lower infection and replication of ancestral SARS-CoV-2, but this may be changing as the virus evolves," Short said.
"Future clinical studies will be needed to validate these preliminary findings in a larger population and to determine the role of other factors, such as antibodies in protecting children from SARS-CoV-2 infection," she noted. (AA/IANS)