Swiss Cheese Model for COVID-19

swiss cheese slices with a family and covid 19 virus image

The Swiss Cheese Model for COVID 19 is an excellent mental tool to visualize COVID 19 prevention strategies at the system level, bird’s eye view.

First, about the Swiss Cheese Model. As emphasized by James Reason, the model’s creator, it invites us to view human errors as a consequence, not as a cause. According to this line of thinking, the error is not a moral problem but a system problem. I have discussed it in the above post.

Swiss Cheese Model for COVID 19

We can apply the Swiss Cheese Model for COVID 19 to visualize and understand COVID 19 prevention strategies. In fact, academics and healthcare practitioners have already applied the model for this purpose. I will discuss their versions here.

Swiss cheese layers with a family and COVID 19 virus
Apply the model for COVID 19

The above image depicts my version. It features the following characteristics.

1. COVID 19 defense layers arranged in levels

The prevention strategies are categorized into three levels: Micro, Meso, and Macro. I bring this group nomenclature from the sociological literature. The following list clarifies what those terms refer to.

  • Micro-level: Individual-level
  • Meso – level: Group or community level
  • Macro-level: Political/policy level

2. The levels in a hierarchical order

The levels are arranged in a hierarchical order. The macro-level layers yield the highest impact. The meso and micro-level layers follow each other respectively. The slices’ increase in size from micro to macro represents it.

3. Each level includes at least two defense layers (slices).

Each level includes at least two layers or strategies (two cheese slices). This is not comprehensive and requires modifications. These layers carry holes of varying sizes and shapes. The holes shift their positions and hence they are dynamic.

  • Micro-level defense layers: Stay at home, face mask, and physical distancing
  • Meso – level defense layers: Community support and lockdowns
  • Macro-level defense layers: Paid sick leave and border control

4. The lower level is dependent upon the adjacent higher level.

Any level cannot withstand by itself; each layer is dependent on its adjacent one. The image depicts it.

The above list of prevention strategies is not complete, and the model deliberately omitted vaccine and testing because its aim is to highlight the relative importance of standard preventive measures. Those interested can include any other measure.

Previous models

Few Swiss Cheese models for COVID 19 exist. The most popular one is the version of Ian Mackay, a virologist from Brisbane, Australia. The New York Times reported it after his version went viral through Twitter. The following is his version.

Ian Mackay’s Twitter on the model

I found a Sinhala version of the Ian Mackay’s version of the Swiss Cheese Model.

File:SwissCheese ver3 SINHALESE.jpg

A Sinhala version of Ian M. Mackay’s adaptation through Wikimedia Commons under the license of CC BY 4.0.

The New Zealand version

Siouxsie Wiles, Associate Professor at the University of Auckland with Toby Morris introduced the following model. It is a very comprehensive one as you can see it. You can read about it in this post of COVID 19 nad Swiss cheese system.


Swiss cheese model for COVID 19 prevention

Source:; New Zealand’s Swiss Cheese model for COVID 19 under the license of CC BY-SA 4.0


Author: Prasantha De Silva

A specialist in Community Medicine board-certified in Sri Lanka and a research analyst in Canada

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