Research led by the University of Queensland has found that children’s nasal linings are better at inhibiting SARS-CoV-2 infections than adults’ noses.
Dr Kirsty Short from UQ’s School of Chemistry and Molecular Biosciences said it could be one of the reasons why children’s immune responses have so far proved more effective at preventing and fighting COVID-19.
“Children have a lower rate of infection with COVID-19 and milder symptoms than adults, but the reasons for this are unknown,” Dr Short said.
“We have shown that the lining of children’s noses has a more pro-inflammatory response to ancestral SARS-CoV-2 than the noses of adults.
“But we found it’s a different ball game when it comes to the Omicron variant.”
The research team exposed nasal lining cell samples from 23 healthy children and 15 healthy adults to SARS-CoV-2.
The results showed that the virus replicated less efficiently in the children’s nasal cells, as well as an increased antiviral response.
Dr Short said there were several theories as to why.
“It could be an adaptation to increased threats from ‘foreign invaders’ such as viruses or bacteria seen in childhood,” he said.
“It’s also possible that increased exposure to these threats in childhood ‘trains’ children’s nasal lining to mount a stronger pro-inflammatory response.
“Or alternatively, metabolic differences between children and adults could alter how virus-fighting genes are expressed.”
The researchers found that the Delta COVID-19 variant was significantly less likely to replicate in the nasal cells of children compared to adults.
But the trend was noticeably less pronounced in the case of Omicron.
“Altogether, it shows that the nasal lining of children supports less infection and replication of ancestral SARS-CoV-2, but this may be changing as the virus evolves,” Dr 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.”
The research was published in PLOS Biology.
Media: Dr Kirsty Short, k.short@uq.edu.au; UQ Faculty of Science media, science.media@uq.edu.au, +61 (0)438 162 687