The nose of children can better counter Covid-19 than that of adults, but not if it is Omicron. This is what researchers at the University of Queensland concluded after analyzing cellular samples of the nasal epithelium (the lining of the nose) of children and adults exposed to some of the variants of Covid-19. The study, published in the journal Plos One, concludes that while the original Covid-19 strain and the Delta variant replicated less efficiently in children’s nasal epithelial cells, this is not the case with Omicron. Results consistent with the increase in the number of pediatric infections that occurred with the spread of the Omicron variant.
Pediatric viruses, after the pandemic they return (and out of season)
by Tina Simoniello
The reasons for “pediatric resistance”
We now know that SARS-CoV-2 causes a wide range of clinical symptoms, including life-threatening acute respiratory distress syndrome. Since the start of the pandemic, children have had a lower rate of Covid-19 infection and milder symptoms than adults. However, the factors behind this apparent ‘pediatric resistance’ to Covid-19 infections are unknown.
To better understand these mechanisms, the researchers took samples of primary nasal epithelial cells from 23 healthy children between the ages of 2 and 11 and from fifteen healthy adults between the ages of 19 and 66. After taking the samples, they exposed the cells of adults and children to Sars-CoV-2 and then observed the ‘kinetics’ of the infection and antiviral responses in children compared to adults.
Covid vaccines for younger children, why approval now? Who should make them?
by Aureliano Stingi
More armored children’s nose
The researchers found that ancestral SARS-CoV-2 replicated less efficiently and was associated with an intensified antiviral response in children’s nasal epithelial cells. This lower viral replication rate was also observed with the Delta variant, but not with the newer Omicron variant.
“We have provided the first experimental evidence that the nasal epithelium may play an important role in reducing children’s susceptibility to Sars-CoV-2,” explain the researchers on Plos One. “The data suggest that children’s nasal epithelium has specific characteristics and that it may offer some level of protection from at least the original Sars-CoV-2 strain.”
Possible explanations for children’s increased resistance may also be the fact that their increased exposure to various viral infections during childhood ‘trains’ their nasal epithelium to create a stronger pro-inflammatory response to any antigenic challenge.
The differences between the nose of adults and children
There is evidence to suggest that nasal epithelial cells (NECs), the first site of infection, are fundamentally different in children than in adults. Gene expression studies using the nasal epithelium of healthy individuals suggest that transcription for the Sars-CoV-2 receptor, the angiotensin-converting enzyme 2 (ACE2), is expressed at lower levels in children than in adults. . However, this has yet to be validated at the protein level.
Children and Covid: how to understand that hospitalization is necessary
by Simone Valesini
Greater antiviral response
But there is more: Pediatric and adult nasal epithelial cells can ‘mount’ a fundamentally different innate immune response to SARS-CoV-2. Recent RNA sequencing of entire epithelium from pediatric and adult proximal airways suggests that there is greater expression of genes associated with inflammation and antiviral response in children than in adults.
The researchers’ conclusions
“Although increased inflammation and interferon production have previously been associated with the high severity of Covid-19 – explain the Queensland researchers – it is important to note that these studies refer to the inflammatory response in the lower respiratory tract, where any immunopathology can lead to respiratory distress. On the contrary, inflammation in the upper respiratory tract plays an important role in the control of early viral replication. In particular, in several studies it has emerged that high levels of type I interferon effectively inhibit the replication of SARS-CoV-2”. Consistent with these data, nasopharyngeal swabs from infected children show higher levels of interferon and inflammatory markers than those from infected adults.
Children, the alarm: physical activity reduced by 20 percent with the pandemic
by Elena Bozzola
The limitations of the study
The researchers note, however, that the sample on which they performed the analyzes is small (just under 40 people) and therefore more clinical studies are needed to validate these preliminary results in a larger population and to determine the role of other factors. , such as antibodies in protecting children from Sars-CoV-2 infection. Furthermore, pediatric protection from emerging variants has yet to be quantified.