Professor James T Reason proposed a layered approach to reducing the risk of accidents due to human error for transmission of Covid.
I really liked this approach for communicating risk reduction. Adapting it creates a simple way to get across that no single intervention (layer) is perfect, Each layer has its failings (holes) that can come and go and be made worse. Using lots of layers provides a better chance of preventing transmission of SARS-CoV-2, the virus that causes COVID-19. You can read the entire article here. In the article, Professor Reason discusses "Holy Thinking" (see below) and how each layer of defense can have its problems. If all the holes line up, transmission can happen.
Where do these holes come from? Let’s look at masks. We know they are good for preventing the wearer from spreading their virus-laden aerosols to others and into the air. They also serve some role in preventing a wearer from inhaling those aerosols. So what causes holes in this imperfect layer of risk reduction? Here are some ideas…
And those are just some of the holes in one layer!