The immune system of infants is said to be more efficient than that of adults. It is for this reason in particular that they are little affected by Covid-19.
- Babies are often sick but their immune system is actually more efficient than that of adults.
- Their immune cells act faster and in greater numbers against pathogens.
What if babies were more resilient than adults? This surprising hypothesis is very real according to a team of researchers who have just published their work in the journal Science Immunology. “The infant’s immune system has a reputation for being weak and underdeveloped compared to an adult, but the comparison isn’t quite fair.underlines Donna Farber, one of the authors of the study. Adults don’t get sick as often (than infants) because we have stored memories of the viruses that protect us (…) when everything the baby encounters is new“So in reality, their immune system is much better at fighting new pathogens!
Baby’s immune cells detect viruses before adult cells
To measure the effectiveness of babies’ and adults’ immune systems, scientists only tested them with new pathogens. The goal is for both parties to be equal. They thus selected immune cells without immunological memories in newborn and older mice. They then placed each of these two cell types into virus-infected mice. And the result is convincing: the immune cells of babies detected lower levels of viruses compared to those of adults, which means that they were able to start fighting them earlier. On the other hand, they acted faster and in greater numbers against the virus, which was less the case with adult immune cells.
Infant’s immune system more efficient than that of adults
“We looked at immune cells that had never been activated, so it’s a surprise that they behave differently with age, develops Donna Farber. What this means is that the infant’s immune system is more efficient and can rid itself of pathogens early in life. In some ways it may be even better than the adult immune system, as it is designed to respond to a multitude of new pathogens”.
Babies, less affected by Covid-19 thanks to their immune system
For the authors, these very good results for babies’ immune cells could explain why they are less affected by Covid-19. “SARS-CoV-2 is new to absolutely everyone, so with this virus we are seeing a natural and egalitarian comparison of the adult and infant immune systemcontinues Donna Farber. Adults confronted with a new pathogen react more slowly. This gives the virus a chance to replicate more and that’s when you get sick”.
Redesigning vaccines for children
Among other lessons from this study, the researchers believe they have understood why vaccines are particularly effective during childhood. It is precisely because the immune cells are stronger. “Most vaccine formulations and doses are the same for all ages, but understanding children’s immune responses could lead to using lower doses and therefore designing more effective vaccines for this age group.“, concludes the researcher.
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