A study has revealed that the untrained immune response of children plays a vital role in helping them falling prey to SARS-CoV-2. When compared with adults, children are more unlikely to get infected with the virus.

“Children are very much adapted to respond – and very well equipped to respond – to new viruses,” says Donna Farber, an immunologist at Columbia University in New York City. Even when they are infected with SARS-CoV-2, children are most likely to experience mild or asymptomatic illness.

This small, young population took scientists by surprise when a trend revealed that only a small percentage of children have been so far succumbed to getting infected by coronavirus or SARS.   Reports say that children’s response to the COVID-19 is better and different from those of adults and that though they may show signs of COVID-19 they rarely test positive on a standard RT-PCR test.

Another study conducted on a family with three children under ten years of age who developed SARS-CoV-2 antibodies, it has been found that two of them recorded mild symptoms, but none of the three tested positive on RT-PCR. The test was conducted 11 times in a span of 28 days, but none tested positive despite being in close contact with their parents during this period.

Melanie Neeland, an immunologist at the Murdoch Children’s Research Institute in Melbourne, studied the family and stated that the children’s immune system sees the virus “and it just mounts this really quick and effective immune response that shuts it down, before it has a chance to replicate to the point that it comes up positive on the swab diagnostic test.”

Studies have also reported that even those children who experienced the rare multisystem inflammatory syndrome in response to SARS-CoV-2 infection have shown positive results on RT-PCR.

According to Farber, children’s antibodies offer clues on what is going on. A study, where 32 adults and 47 children were observed, revealed that children mostly produced antibodies that were aimed at the SARS-CoV-2 spike protein. It is this protein that the virus uses to enter cells in the human body. Adults, though they had similar antibodies, they also developed antibodies that were against the nucleocapsid protein. This protein enhances viral replication. The kids did not develop nucleocapsid-specific antibodies; this suggests that they were not experiencing widespread infection.

While Farber says that the reason children can neutralize the virus because their T cells are relatively naive. But there is other evidence that suggests the situation is not so straightforward.

Alasdair Munro, who studies pediatric infectious diseases at University Hospital Southampton, UK, says “There’s been some suggestion that the rapidity and scale of their innate immune response might be protective against the initiation of infection.” However, this effect is difficult to study, and raises questions regarding why it is not seen with other viruses that can cause severe disease in children, he says.

Further studies suggest that children are prone to seasonal coronaviruses that cause common cold. It is likely that the antibodies they have developed might confer some protection against SARS-CoV-2.

Source: Nature
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