Is the Hygiene Hypothesis True?

[BootinUp]

Published October 25, 2022
By Caitlin Rivers
Johns Hopkins Bloomberg School of Public Health


Did Covid shutdowns stunt kids' immune systems?

The hygiene hypothesis is the idea that kids need to be exposed to germs in order to develop healthy immune systems. We know that many common viruses did not circulate as widely during the pandemic, thanks to social distancing, masking, and other COVID mitigation measures. Are there downsides to those missed infections?

In this Q&A, Caitlin Rivers speaks with Marsha Wills-Karp, PhD, MHS, professor and chair of Environmental Health and Engineering, about the role of household microbiomes, birth, and vaccines in the development of kids’ immune systems—and whether early exposure really is the best medicine.

This Q&A is adapted from Rivers’ Substack blog, Force of Infection.

I THINK THERE’S SOME CONCERN AMONG PARENTS WHO HAVE HEARD ABOUT THE HYGIENE HYPOTHESIS THAT THERE IS A DOWNSIDE TO ALL THOSE STUFFY NOSES THAT DIDN’T HAPPEN [DURING THE COVID-19 PANDEMIC]. ARE THERE ANY UPSIDES TO VIRAL INFECTIONS? DO THEY HELP THE IMMUNE SYSTEM IN SOME MEANINGFUL WAY?

I don’t think so.

You mentioned the hygiene hypothesis, which was postulated back in the ‘80s. German scientists noticed that families with fewer children tended to have more allergic disease. This was interpreted [to mean] that allergic disease was linked to experiencing fewer infections. I have explored this idea in my research for a couple of decades now.

This phenomenon has helped us to understand the immune system, but our interpretation of it has grown and expanded—particularly with respect to viruses. Almost no virus is protective against allergic disease or other immune diseases. In fact, infections with viruses mostly either contribute to the development of those diseases or worsen them.

Continued https://publichealth.jhu.edu/2022/is-the-hygiene-hypothesis-true