Did getting exposed to fewer germs for the last 2 years weaken our immune systems?

Biology/Immunity Families/Kids

A: Not likely. If your kids are suddenly getting sick a lot, this is likely due to “catching up” on exposures rather than a weakened immune system.


Many families with young kids have been hunkered down for the better part of two years– a good % of a young child’s entire life. While isolation had *many* downsides, I think we can agree that not having to suction snot out of infant noses or clean up norovirus puke was a happy upside.

But did this lack of infectious exposures weaken our immunity, especially for young kids? We’re getting this question a lot, and you can breathe easy (so to speak). Developing immune systems constantly “sample” microbes from the environment to learn what’s friendly or not, and there are plenty of those to be found in within our interactions with family, pets, and the natural environment (let them eat dirt!). If your kids spent more time outside during the pandemic, that may have even been a net positive for their immune system.

While it may seem that the developing immune system “needs” lots of infections to learn, in truth we evolved in small groups of humans, not crowds. While some infections have been with us for that long (H Pylori, herpesviruses), most infections we are familiar with today evolved much later as “crowd” infections when people started gathering in more dense settlements and cities.

We don’t *need* exposure to these infections to develop our immune systems– in fact we’ve been much better off in the last hundred years as we’ve lowered the burden of infections through vaccination and improved sanitation (no one’s missing measles, smallpox, or tuberculosis, am I right?)

With the precautions taken for COVID-19, we saw influenza transmission drop to almost zero. Admissions for asthma attacks also went down dramatically, likely due to avoidance of common respiratory infections that trigger asthma. This suggests there are real benefits to avoiding infections with common pathogens.

But what about now, why do our kids seem continuously sick with activities resuming? First, we may have forgotten just how often young kids were sick pre-COVID, with an estimated 6-8 upper respiratory infections a year for the average child. Runny noses, pink eye, strange rashes, and stomach bugs are all familiar signposts along the young parenting gauntlet.

There is some evidence that kids who get more infections early in life in daycare get fewer infections when they enter elementary school. But the total number of infections was similar, suggesting that non-daycare kids are catching up on exposures others already had, rather suffering from a “weak” immune system. The total number of infections is not different, just the timing. This is likely what’s happening now–we are playing catch-up from the previous two years as we resume social contact.

As with SARS-CoV-2, if you can avoid infection with more common respiratory or gastrointestinal infections, this is all for the good. Infections may contribute to the education of our immune system by building memory, but this is like learning a stove is hot by getting burned rather than someone warning you. Vaccines and prevention measures protect us against nasty illnesses without paying the high price of infection.


We “need” most infectious pathogens….like we need a hole in the head. Humans have no inherent need for exposure to smallpox, cholera, measles, polio, etc, and this is also true of less severe but common respiratory infections.

The human immune system needs plenty of exposure to friendly microbes in the natural environment to help educate the immune system. So let your kids get outside, garden and play in the dirt. If you haven’t been sick the last two years and are now playing catch-up, hang in there. There is no magic for boosting your immunity—stick to the basics of good nutrition, sleep, and lowering stress. Your immune system is still looking out for you!


Those Nerdy Girls


Additional Links: