‘Good germs’ keep us healthy. Scientists fear we’re killing them with all the COVID sanitizing

Written by Danielle Chiriguayo and Amy Ta, produced by Brian Hardzinski

At the start of the pandemic, when people knew nothing about how COVID-19 spread, hygiene theater was in overdrive. That meant wiping down every counter, tabletop, and doorknob — and even disinfecting groceries. A lot of that overdrive turned out to be overkill. 

Many of these pandemic habits will be hard to break, but we might have to do that because some germs are good. Certain microbes and bacteria protect our bodies and keep us healthy. 

Earlier this year, a group of scientists published concerns about the effects of all this sanitizing and spraying down once the pandemic ends.

One of the study’s authors is Brett Finlay, microbiologist and immunologist at the University of British Columbia, and author of “Let Them Eat Dirt: How Microbes Can Make Your Child Healthier.”

Finlay says that from birth, humans coexist with bacteria, fungi, and viruses, and each has a different biological function. They’re involved with how the brain plus intestinal and immune systems develop. 

Finlay says he’s concerned about how immune systems of all ages are developing due to pandemic-driven cleanliness. Before COVID, he says it was common for humans to swap microbes. That includes through kissing, where people can transfer 18 million microbes in one simple act. 

“We've all been living in these cocoons last year, and we're not getting normal microbe exposure. A new kid born into this world, yeah they might not get a cold, but they're not getting all the other microbes that they normally also get if they went to daycare and things. … You're just not getting exposure to the normal microbes.”

He points out that only about 100 microbes can actually cause diseases. “They're with you for life. … Being human is being coated in microbes.”

If humans are deprived of microbes, Finlay notes they can become asthmatic or obese. He cites research that found babies born via cesarean section (as opposed to vaginal birth) have a 25-30% higher chance of developing asthma later in life and a 30% chance of becoming obese. 

Finlay points out that new research suggests microbes might play a role in the development of cardiovascular disease and Alzheimer’s. He uses the example of the Hygiene Hypothesis that states humans are living too cleanly today. 

“We went on a war against microbes, because we would then solve infectious disease. We brought in sanitation and antibiotics and vaccines,” he says. “What we now realize is that in our quest to clean the world up, we're actually wiping out the good microbes. So the lack of these good microbes and the increase of these not-so-good microbes seems to be involved in causing these diseases that we really didn't see much of before.”

Moving forward, he says the best way to improve one’s immune system is to become more aware of everyday actions. That includes improving diets, hugging dogs, and interacting with people. … It’ll also pay off to eventually cut back on excessive hand washing and using hand sanitizer. 

“We've evolved to be exposed to microbes. And if we don't have the serious life-threatening infectious diseases around, then there's no reason to be wearing these masks, washing our hands, and avoiding contact.”



  • Brett Finlay - microbiologist and immunologist at the University of British Columbia, and author of “Let Them Eat Dirt: How Microbes Can Make Your Child Healthier”