Isolation and sanitation during COVID-19 may affect human microbiome, scientists say

A nurse sanitizes a man's hands prior to a test at a temporary COVID-19 clinic in Montreal, on May 12, 2020. Paul Chiasson / THE CANADIAN PRESS

VANCOUVER — As people around the world remain isolated in their homes, avoiding close contact with others and meticulously sanitizing their hands and surfaces, scientists warn there may be unintended consequences of these necessary pandemic protocols.

While it's important to follow public health orders to reduce spread of COVID-19, experts say that all the antibacterial wipes and physical distancing could have long-term impacts on our microbiomes -- the collection of microbes that live on and inside our bodies.

When we hug someone, travel to another country or get our hands dirty, we acquire new microbes, said Brett Finlay, a University of British Columbia microbiologist. Although some microbes can make us sick, others are good for us, and a diverse and rich microbiome is essential to our health, he said.

Finlay said the discovery of pasteurization in the late 1800s kicked off about a century of society being "hellbent" on getting rid of microbes, and infectious diseases declined as a result. But the loss of microbial diversity has been linked to conditions including asthma, obesity, diabetes and brain and cardiovascular diseases, he said.

So, especially over the past decade, experts like Finlay, who co-wrote a book titled "Let Them Eat Dirt: Saving Our Children from an Oversanitized World," have been trying to persuade people to be a little less afraid of germs.

"We were cruising along, starting to realize these microbes are good. Maybe we shouldn't wipe them all out. Maybe we should let our kids play outside and maybe we don't have to use hand sanitizer five times on the playground," Finlay said.

"Then COVID hit and that has thrown a wrench in everything."

Finlay recently co-authored a paper published in the Proceedings of the National Academy of Sciences that called for more study of how this extended period of near-global lockdown has changed our microbiomes and could affect human health long-term.

The paper was the result of ongoing discussions at research organization CIFAR's humans and the microbiome program, where Finlay is co-director. It says we could see impacts to global immunity, allergies and rates of conditions like asthma and diabetes.

It also points out that the COVID-19 pandemic could deepen social inequalities, with changes to the microbiome depending on whether someone lives in a high- or low-income country and their access to health care, clean water, sewage systems and healthy food.

But Finlay noted there are things people can do to promote a healthy microbiome while following COVID-19 rules. Spending time outdoors, gardening, exercising, eating a fibre-rich diet, avoiding unnecessary antibiotics and having physical contact with members of your household and pets can all help, he said.

Kathy McCoy, scientific director of the University of Calgary's International Microbiome Centre, said she expected the intense focus on hygiene during the COVID-19 pandemic to have a "dramatic" effect on people's microbiomes.

She said the microbiomes of most healthy adults without underlying conditions should "bounce back" after the pandemic, though, as long as they don't gain weight during this time.

But she also said inequality will play a major role -- people who can work from home may be cooking more and eating healthier meals than usual, while those who have lost their jobs may have to rely on food banks or cheap, processed food.

Both Finlay and McCoy cautioned that babies born during the pandemic could experience lifelong impacts.

McCoy said early life is an important period of time for developing the immune system through exposure to microbes. Newborns birthed through caesarian section are already exposed to fewer important bacteria at the start of their lives.

Now, during the pandemic, parents may be more hyper-vigilant in bathing their babies and cleaning their homes, she said, and babies are having far less interaction with adult members of their extended family or other infants who could pass on their microbes.

"Babies not being able to interact with their grandparents or other babies, just (not) having that really solid immune education in early life, I worry: what are the long-term implications of that?"

She said it would be worthwhile to follow a cohort of babies born during the pandemic and compare their microbiomes with older data of babies born pre-COVID-19. The rates of immune diseases, such as asthma and allergies, should also be monitored over time to see if there is a spike associated with infants born now, she said.

There are steps parents can take to improve their babies' microbial health during COVID-19, including breastfeeding if possible, playing outdoors and getting a pet. Babies raised in homes with dogs have been shown to have lower rates of asthma and allergies.

McCoy said post-pandemic, we have to find a balance between avoiding infection and building a healthy, diverse microbiome.

"We don't know that balance yet, but we have to try to keep understanding this relationship," she said. "Maybe if we try to learn from this pandemic, we'll be better prepared for the next one."

This report by The Canadian Press was first published Feb. 21, 2021.