Babies' Immune Systems May Stand Down To Let Good Microbes Grow

Here's possible solace for parents who are up at night with a baby who gets sick all the time: There appears to be a good reason why infant immune systems don't fight off germs.

A newborn's immune system is deliberately not doing battle with every germ that comes along so that "good" microbes have a chance to settle in, researchers say. That explanation is at odds with the widely held belief that those new immune systems are just too weak to do the job.

Evidence has been mounting that most of the trillions of bacteria, fungi and other microbes that inhabit the human body are actually helpful. They seem to perform crucial functions, such as helping fight off pathogens and teaching our immune systems how to function properly in the long term.