When it comes to fending off new viruses, baby has Mom and Dad beat.
An infant's immune system is better than an adult's at combating new viruses, researchers say.
Compared to adults, babies get a lot of viral respiratory infections, but babies are dealing with these viruses for the first time, study author Donna Farber pointed out.
“Adults don't get sick as often because we've recorded memories of these viruses that protect us, whereas everything the baby encounters is new to them," said Farber, a professor of microbiology, immunology and surgical sciences at Columbia University.
To assess the immune system's ability to respond to a new virus, her team collected naive T-cells -- immune cells that have never encountered a pathogen -- from both baby and adult mice. The cells were placed into an adult mouse infected with a virus.
Compared to adult cells, the cells from the babies detected lower levels of the virus, multiplied faster and arrived in greater numbers to the site of infection. As a result, they rapidly mounted a strong defense against the virus, according to findings published Dec. 10 in the journal Science Immunology.
Lab experiments also showed similar advantages for infant T-cells compared to adult T-cells.
“We were looking at naive T-cells that have never been activated, so it was a surprise that they behaved differently based on age,” Farber said in a Columbia news release. “What this is saying is that the infant's immune system is robust, it's efficient, and it can get rid of pathogens in early life. In some ways, it may be even better than the adult immune system, since it's designed to respond to a multitude of new pathogens.”
The COVID-19 pandemic seems to provide proof of that, the researchers said.
“SARS-CoV-2 is new to absolutely everybody, so we're now seeing a natural, side-by-side comparison of the adult and infant immune system,” Farber said. “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 study also helps explain why vaccines are particularly effective in childhood.
“That is the time to get vaccines and you shouldn't worry about getting multiple vaccines in that window,” Farber said. “Any child living in the world, particularly before we started wearing masks, is exposed to a huge number of new antigens every day. They're already handling multiple exposures.”
The findings could help improve childhood vaccines.
“Most vaccine formulations and doses are the same for all ages, but understanding the distinct immune responses in childhood suggests we can use lower doses for children and could help us design vaccines that are more effective for this age group,” Farber said.
The U.S. National Institute of Allergy and Infectious Diseases has more on the immune system.
SOURCE: Columbia University, news release, Dec. 10, 2021