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Arguing with your family or friends about using masks to lower Covid risk? “Swiss Cheese” can help!

By Dr. Sarika Arora, MD

Covid-19 is nothing to laugh about. And for many women, the debates with family and friends about wearing masks or social distancing can sometimes seem like civil war, pitting sister against sister.  

Women wearing masks

The truth is this virus doesn’t have an opinion about masks, shutdowns, school closings, rapid testing or contact tracing. Or politics. It just hunts victims.  

It’s so good at finding people to infect, there’s no single method of protection that is foolproof except total isolation — and that’s just not possible or practical for most of us.

So, let’s engage in a helpful thought experiment. Imagine slices of Swiss cheese.  Each slice has a lot of holes in it. But if you layer one slice on top of another, the cheese eventually covers all the holes, so there is no path through.

In this picture, every step you’re taking to reduce Covid risk is just one slice of Swiss cheese. The question isn’t whether masks or testing are perfect. You need multiple slices of cheese to be protected. And the more at risk you feel, the more layers you need.  

Epidemiologists and other virus experts have begun to embrace this “Swiss Cheese Model” as a way to help people understand how all the tools we have at our disposal to fight Covid-19 — though each is imperfect — really can stack up to make a difference. 

This idea of layered protection in a public health emergency has actually been around since the 1990s. But “Swiss cheese” may finally be having its moment during the current pandemic because it’s just such a commonsense way to think about what’s needed to stay safe. A new feature article in the New York Times even provides a nifty infographic to illustrate the point. NPR and the Wall Street Journal have also covered the Swiss Cheese model in recent weeks. It’s enough to make you hungry!

In all seriousness, I’m for anything that makes it easier for us to understand how to protect ourselves and lower infection risk. I’ve been especially interested in reading about the slices of protection we’re being recommended to layer — and I want to add to this conversation by mentioning a very important slice that seems to be missing.

The layers that are getting a lot of buzz are personal behaviors, like masks, hand washing and social distancing, and public health measures like public education, improved ventilation in indoor settings, and vaccines. 

Nowhere have I seen mentioned the vital layer of our own natural immune defenses. When our immune system is functioning as it should, in many ways, it’s like that rare slice of Swiss cheese that comes with only a few tiny air bubbles.

Think about it. When a virus enters one of your cells and infects it, the infected cell is programmed to immediately display a warning flag protein on its surface as an alert to your immune system. Another protein produced by the infected cell (called an Interferon) tries to “hold the line” and stop the virus from replicating while the cell waits for help to arrive. In our bloodstream, immune T Cells circulate, on the lookout for the warning flag proteins. When one is spotted, T Cells release cytotoxic substances to destroy the infected cell. From there, other immune cells are signaled to get in on the action, including phagocytes that eat up viruses like mini Pac men.  

This initial response is part of why the dose of the original infectious exposure matters so much. If you aren’t exposed to much of the virus, your immune system may be able to zap infected cells before the virus outruns it.  (Kids seem to be especially good at this stage, which is probably why so many deal with the infection without ever developing symptoms.) 

It’s also the reason why supporting your immune system is so important. You want your immune response to be ready for action. In many ways, your immune system is like it’s own Swiss cheese sandwich. You want to close up any holes there too. 

Who knew that a simple deli staple could teach us so much about Covid-19 and protecting our own health? If this idea of layering up protection against Covid speaks to you as much as it does to me, I encourage you to add this extra slice of your own powerful immune system. 

The other nice thing about the Swiss Cheese Model is that it disarms the ideologues who have to win every argument about the science of Covid. It moves the debate to more neutral ground: you don’t have to prove or disprove the value of any one line of defense; in fact, we need to layer up a bunch of them.   

Connect with me on Facebook to let me know how you’re staying safe!


Last Updated: December 28, 2021
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