Why infants are less affected by COVID than adults

Credit: CC0 Public Domain

As any parent knows, infants are prone to getting respiratory infections.

In a new study from Columbia University, researchers found that the infant immune system is stronger than most people think and beats the adult immune system at fighting off new pathogens.

Babies do get a lot of respiratory illnesses from viruses, like influenza and respiratory syncytial virus, compared to adults. But unlike adults, babies are seeing these viruses for the first time.

In the study, the team tested the immune system’s ability to respond to a new pathogen, essentially eliminating any contribution from immunological memories.

For the head-to-head comparison, the researchers collected naïve T cells—immune cells that have never encountered a pathogen—from both infant and adult mice. The cells were placed into an adult mouse infected with a virus.

In the competition to eradicate the virus, the infant T cells won handily:

Naïve T cells from infant mice detect lower levels of the virus than adult cells and the infant cells proliferated faster and traveled in greater numbers to the site of infection, rapidly building a strong defense against the virus.

A laboratory comparison found similar enhancements among human infant compared to adult T cells.

That appears to be playing out in the case of COVID. SARS-CoV-2 is new to absolutely everybody, so researchers are seeing a natural, side-by-side comparison of the adult and infant immune system

And the kids are doing much better. Adults faced with a novel pathogen are slower to react. That gives the virus a chance to replicate more, and that’s when you get sick.

The findings also help explain why vaccines are particularly effective in childhood, when T cells are very robust.  The study could lead to better vaccine designs for children.

If you care about COVID, please read studies about why bald men may have higher risk of severe COVID-19 and results showing how to overcome COVID-19 pandemic fatigue.

For more information about the pandemic, please see recent studies about many Americans take immune-weakening drugs that may lower COVID vaccine response, and findings that COVID-19 booster shots prompt stronger, longer protection than original shots.

The study is published in Science Immunology. One author of the study is Donna Farber, Ph.D.

Copyright © 2021 Knowridge Science Report. All rights reserved.