Because of their powerful early ‘innate’ immune response, children have avoided serious COVID-19 symptoms. And now, according to a study spearheaded by experts at Australia’s Garvan Institute of Medical Research, we know what this may entail for the immune system. Children’s immune systems, unlike those of adults, do not recall the virus and do not adapt, meaning that when exposed to SARS-CoV-2 again, the child’s body still perceives it as a fresh danger.
In exchange for their proficiency in eliminating the virus the first time around, youngsters are left without the chance to create ‘adaptive’ memory that would protect them the next time they are exposed to the pathogen.
Children are said to have a “naive” immune system since they have not been exposed to numerous infections. Because they don’t create memory T cells, they’re more likely to become ill if they’re reinfected. Their T cells, like the T cells in older individuals, are at danger of becoming ‘exhausted’ and ineffectual with each successive viral episode as they age. Because of this, we believe that childhood vaccinations are crucial.
There are “fight” and “flight” states in the immune system. The innate immune system is the body’s initial line of defense against infection. It consists of the skin and the mucosal surfaces, which act as physical barriers to keep out viruses. It’s made up of cells that produce chemicals to send messages to other cells and guard against viruses. Viruses of all kinds are treated the same by the body’s innate immune system.
Adaptive immune system cells like B and T lymphocytes form the second line of defense. These cells feature receptors that allow them to quickly identify and respond to certain viral components.
Researchers discovered that infants’ immune systems are essentially blank at birth, with a disproportionately large number of naive T cells. Memory T cells replace naive T cells, which can only respond to viruses they have seen previously, when a person ages and is exposed to more viruses.
Your immune system learns from your experiences with infections and improves with time, enabling you to mount a more rapid response that is more precisely tailored to the viruses that have previously attacked you. As kids become older and are less effective at clearing infections, they require their adaptive immune systems to step in and help out more.
Clinical Immunology reports on an in-depth look at T cells and cellular immune responses in a small sample of children and their home family contacts with moderate or no symptoms from coronavirus (SARS-CoV-2) infection. The research was conducted by Professor Phan, Associate Professor Britton, and colleagues.
Researchers sequenced samples of white blood cells to examine T cells in kids and adults during the acute infection and a month afterwards. Scientists were able to account for the effect of genetic and environmental factors on the immune response by studying affected people’s close household connections.
While adults had fewer naive T cells and better memory T cell responses after recovery, the researchers observed that children have a wide variety of naive T cells capable of fighting SARS-CoV-2.
What’s interesting about the results is that they explain why certain older persons have an immunological overreaction to SARS-CoV-2.
When adults are exposed to SARS-CoV-2 for the first time, their memory T cells can only identify previously encountered strains. This might cause an inappropriate immune response that is not focused at SARS-CoV-2. As the immune system cranks up to attempt to heal the issue, the virus has a chance to spread uncontrolled and produce more severe symptoms.