Children’s noses may be better than adults’ at defending against infection because of “pre-activated” immunity against the coronavirus, a new study suggests.
Researchers analysed nasal swabs from 45 infected patients, including 24 children, and from 42 healthy individuals, including 18 children. In nasal-lining cells and immune cells from the children’s swab samples, they saw higher levels of genetic material that can sense the presence of the virus and trigger the immune system to defend against it.
The study group included ages 4 weeks to 77 years.
Higher amounts of these sensors result in stronger early immune responses in children than in adults, according to a report published on Wednesday in Nature Biotechnology https://go.nature.com/3xSRvLf.
The nasal samples from the children were also more likely than adult samples to contain immune cells known as T cells that play roles in fighting infection and in developing long-lasting immunity, the researchers found.
“We observed striking differences between the paediatric and adult study participants regarding the composition of the immune cell and epithelial cell compartment in the nasal mucosa,” the authors say.
While immune cells were rarely detected in nasal samples from healthy adults, samples from SARS-CoV-2-negative children contained high amounts of almost each immune cell subset with an overall dominance of neutrophils, they added.
“Our data provide clear evidence that the epithelial and immune cells of the upper airways (nose) of children are pre-activated and primed for virus sensing. This is likely a general feature of the children’s mucosal immune response, but of particular relevance for SARS-CoV-2.”
Ultimately, the authors concluded, the effects may lead to a reduction in the ability of the virus to reproduce and help children to clear it from the body faster. “In fact,” they added, “several studies already showed that children are much quicker in eliminating SARS-CoV-2 compared to adults, consistent with the concept that they shut down viral replication earlier.”
The study was supported by the BIH COVID-19 research programme and the [email protected] initiative, the European Commission through Horizon 2020 and the German Federal Ministry for Education and Research.