A lot of interest in this comment. So let me lay out a framework for assessing risk in general and how it relates to Covid so we have a more nuanced understanding of “risk” and risk mitigation.
3 things can determine risk:
-probability
-severity
-time
1/N
3 things can determine risk:
-probability
-severity
-time
1/N
https://twitter.com/amarkinthailand/status/1492370535174447107
2/ Looking to lessons learned in wilderness education and mountaineering, risk can be understood as a combination of these 3 factors. And we have varying control over each of them in different settings. We do this all day long but don’t consciously think about it.
R=P*S*T
R=P*S*T
3/ In simple terms, P (probability) is just how likely is something to happen?
S (severity) is how bad would it be?
T (time) is how long you are at risk/exposed to the hazard.
Unpacking this from just “risk” helps tremendously with thinking about Covid.
S (severity) is how bad would it be?
T (time) is how long you are at risk/exposed to the hazard.
Unpacking this from just “risk” helps tremendously with thinking about Covid.
4/ So practically speaking, how do we lower our risk?
We find ways to lower P, S, and T where possible.
The challenge is sometimes we cannot lower all three, but we usually can lower at least one or two.
We do this every day with driving a car.
We find ways to lower P, S, and T where possible.
The challenge is sometimes we cannot lower all three, but we usually can lower at least one or two.
We do this every day with driving a car.
5/ When driving a car, we use a seatbelt (lowering severity in case of an accident), and we drive sober (drunk driving is a problem because it increases probability) and avoid dangerous conditions (like icy roads). & in bad conditions lower T by spending less time driving.
6/So what about Covid?
We want to lower one or more of each factor (S, P, and T) that combines to create a high risk situation.
We want to lower one or more of each factor (S, P, and T) that combines to create a high risk situation.
7/ Existing mitigations can each be though of as lowing S, P, and even T.
Masks, for example, help lower P (the probability of catching Covid), and if initial viral load does impact how bad it is, it probably also lowers S (severity)
Masks, for example, help lower P (the probability of catching Covid), and if initial viral load does impact how bad it is, it probably also lowers S (severity)
8/ Vaccinations are probably mostly about lowering S, severity, in case you do catch it. (They may also lower P in general if vaxxed ppl are less likely to pass it on or catch it).
Home isolation, or lockdowns, are all about lowering T (time) to zero.
Home isolation, or lockdowns, are all about lowering T (time) to zero.
9/ So how does this help us understand what we can do with Covid?
Wearing a mask* ⬇️ P
Vaccination ⬇️ S
Short trips / not going out? ⬇️ T
*and type of mask changes P with N95s lowering it more than surgical masks
Wearing a mask* ⬇️ P
Vaccination ⬇️ S
Short trips / not going out? ⬇️ T
*and type of mask changes P with N95s lowering it more than surgical masks
10/ How about if I have to fly? I cannot change “T” since the time is fixed.
So I want to lower P and S as much as possible.
So be vaccinated and wear the best mask/respirator you can, and don’t take it off.
R = ⬇️ S * ⬇️ P * T
So I want to lower P and S as much as possible.
So be vaccinated and wear the best mask/respirator you can, and don’t take it off.
R = ⬇️ S * ⬇️ P * T
11/ How about ventilation? Massively ⬇️ R, and if initial dose impacts S also helps ⬇️ S.
Walking outside? If there are not a lot of people out the cumulative T is ⬇️.
Outdoor concert? You’re in one place in a crowd for an extended period? ⬆️ T
Walking outside? If there are not a lot of people out the cumulative T is ⬇️.
Outdoor concert? You’re in one place in a crowd for an extended period? ⬆️ T
12/ You can never get risk to zero (and most reasonable people know this) but you can MANAGE the risk in a responsible way. That’s what laws about not driving drunk are all about. You can drink, or you can drive, but not both since drunk driving ⬆️ P of an accident so much.
13/ This is why removing masks too soon is so problematic. We loose a chance to reduce P.
This is also why vaccine mandates are so helpful, they reduce S and protect our health care system.
This is also why vaccine mandates are so helpful, they reduce S and protect our health care system.
14/ So, risk isn’t monolithic.
R=P*S*T
Even if you are in a “high risk” situation, stop and break things apart and see where you can do one or more things to ⬇️ P, ⬇️ S, & ⬇️ T
R=P*S*T
Even if you are in a “high risk” situation, stop and break things apart and see where you can do one or more things to ⬇️ P, ⬇️ S, & ⬇️ T
15/ Immunocompromised? Your S (severity) is ⬆️⬆️⬆️ so it makes sense to compensate for a high S by wearing an N95 or better to ⬇️⬇️ P as much as you can, and ⬇️ T by limiting contact.
End/ I hope this is helpful for assessing personal as well as institutional risk.
Our organization actually uses this as we are planning classes, field studies, internships, and more.
I’ve also found this helpful with both skeptical and fearful ppl.
Good luck!
Our organization actually uses this as we are planning classes, field studies, internships, and more.
I’ve also found this helpful with both skeptical and fearful ppl.
Good luck!
Postscript/ Please share and pass on if you find this risk framework helpful for thinking about Covid.
@gregggonsalves
@EpiEllie
@GYamey
@kprather88
@dianaberrent
@aetiology
@gregggonsalves
@EpiEllie
@GYamey
@kprather88
@dianaberrent
@aetiology
If this is helpful post examples of what you’ve done!
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