Page 4 - Bow Tie for understanding COVID-19

But Barriers Degrade

100% perfect physical separation will stop all infections, but things degrade this perfection, so we
have government guidance (or “controls”) to try and minimise the holes developing in the barriers.
If the controls work perfectly then the barrier will continue to work.

So the Self Isolation barrier, which physically separates me from infected people can fail due to two
main degradation factors:

PPE (masks and screens), the next barrier is an effective barrier but can degrade due to
unavailability, people not knowing how to use them, etc. but this would probably need its own bow
tie.

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