Kady M.
3 min readMar 10, 2021

There are four groups of people who read that title:

  1. You didn’t take life science courses, and you think that this might be a nice article about a new Italian restaurant.
  2. You did take life science courses, forgot what that meant, and I just gave you an unpleasant flashback to something you would have rather forgotten.
  3. You did take life science courses, work in specific areas of life science related to these terms, and therefore know EXACTLY what they means, or
  4. You’re a high school Latin nerd, and got all excited to see Latin. :-)

Anyway. :-)

In Vitro refers to the testing of a process in a controlled, laboratory environment. In Vivo, on the other hand, refers to the “testing” (so to speak) of that same process in a real world environment, exposed to other variables that might be present in said environment.

The difference between the two is well known to those heroes of science who create vaccines. It is not uncommon for a vaccine to utterly destroy a pathogen in a test tube in vitro, but when animal or human in vivo testing starts, find that the vaccine is utterly useless. For lots of reasons.

Well, the same sort of discrepancy has popped up with, of all things, mask wearing.

One of the unpleasant byproducts of the COVID pandemic has been to produce a subclass of moral scolds who will not only mercilessly berate mask-critics on social media, but also do so in real life, where their utter indignation at individuals choosing to bareface sometimes turns to physical confrontation.

For example:

The unfortunate part of all this rancor is that mask-wearing appears very much to be one of those things affected by “InVitro vs InVivo”.

How? Well, scientific study after study has proven that mask wearing reduces both the amount of viral load expelled by an infected individual and inhaled by a healthy one, thus lowering risk for contagion rather significantly. Good news.

However, these studies have been done either under lab conditions or in semi-controlled environments so data can be gathered. In other words, “In Vitro.”

Unfortunately for those studies, however, when we look at mask-wearing in broad populations over time, In Vivo, well, the advantages are….somewhat hard to find.

Now, I’m not suggesting we dispense with masks. I tend to believe that in certain environments they probably do a lot of good; it’s just that as a population, we spend more time outside our homes in environments which they don’t do much good. The 60-foot-ceiling inside of Home Depot or Wal-Mart, along with its industrial strength air conditioning units, probably isn’t tremendously different, in terms of risk of contagion, with a stroll outside in the park, as long as reasonable distancing is observed. Lots of space with clean air being piped in and bad air being filtered out.

But for mercy’s sake, stop throwing rhetorical bombs (or worse, fisticuffs) at people not as dedicated to their masks as you think they should be. It gets us nowhere, divides us even more than we are otherwise, and is generally counterproductive as we move through what we hope are the latter stages of the pandemic. In Vivo, we find that the difference between masking and not is simply not as huge as those In Vitro studies originally indicated.



Kady M.

Free markets/free minds. Question all narratives. If you think one political party is perfect and the other party is evil, the problem with our politics is you.