Assessing COVID Risk - 18 Factors
What are all the factors you need to consider when assessing risk? These can be broken down in different ways, but here's my comprehensive list of what contributes to risk. In no particular order:
1/21
1. Indoors or outdoors - the most significant factor. For the rest of our lives, outdoors will always be the lowest risk place to gather. It's the easiest way to reduce risk. Doesn't mean no risk, but significantly reduced. Outdoors is essentially ideal ventilation.
2/21
2. Your mask - the more leakage through your mask, the higher dose you'll inhale and the more likely you'll get infected. You want a mask which minimizes leakage. The times in this table no longer apply, but the leakage factors remain.
3/21
3. The infected person's mask - this is the purpose of mask mandates. 2-way masking is more effective than 1-way masking. The infected person wearing a properly fitting respirator can significantly reduce risk.
4/21
4. Distancing - initially when you breathe out, the aerosols are more concentrated, so you can get infected at short range in a shorter time than if you are distanced. Distancing increases the time required until infection.
pubmed.ncbi.nlm.nih.gov/34704625/
5/21
5. Community case rates
6. # of people at the place.
7. Type of people you are meeting – are they COVID cautious? How many contacts do they have? Do they have immunity (see below)?
These three factors combine to determine the chance of encountering infectious people.
6/21
8. Activity - aerosol production - exercising, singing, shouting, breathing all produce different amounts of aerosols. Sitting and breathing produce fewer aerosols. More aerosols generated means higher risk. Gyms are higher risk than libraries.
7/21
9. Activity - breathing rate - The higher the breathing rate, the more air you are inhaling in a given time and higher chance you inhale an infectious dose.
8/21
10. Time you are there - getting infected is about the virus concentration and the number of breaths. Number of breaths is the breathing rate and time. Longer the time, the more dose you inhale and higher risk of infection.
9/21
11. Time the infectious person is there - the more the infectious person has breathed out, the greater the quantity of virus laden aerosols. If they've been through the space briefly, the concentration will not be as high.
10/21
Immunity - there are different types of immunity and I'll go through them. First a disclaimer, I generally don't like discussing this because it's not my expertise. I'm discussing these in general. It's not advice.
Here are the types:
technologynetworks.com/immunology/art…
11/21
How these factors apply to COVID changes depending on your personal immune system, the variant, time since infected or vaccinated and other factors.
Ask a doctor for more details.
My approach is to get fully vaccinated and avoid infection. It's worked so far.
12/21
I'm discussing risk of infection. Vaccines are the best tool to prevent severe disease.
Depending on the variant, immunity can also reduce your viral load or time you are infectious, making you less likely to transmit to others if you do get infected.
13/21
11. Innate immunity - the only thing that has more junk than air cleaning products is immunity boosters. Poor humidity and temperature can impair innate immunity.
nature.com/articles/s4159….
14/21
For active immunity, the factors are:
12. Your vaccine induced immunity
13. Your infection acquired immunity
14. Other's vaccine induced immunity
15. Other's infection acquired immunity
There are also combinations called hybrid immunity.
cdc.gov/vaccines/vac-g…
15/21
16. Public health measures - these include excessive hand washing, plexiglass, face shields and sanitizing pens after signing forms. Ignorance about COVID significantly increases risk. Run away as fast as possible.
16/21
16. (For real this time) Air quality measures – This is what I spend most of my time discussing. Ventilation, filtration and UV all reduce the concentration of active virus particles you can inhale which reduces risk.
17/21
17. Climate - The space temperature and humidity affect the decay rate, deposition rate and your own innate immunity all affecting risk of infection. The same space is higher risk in winter than summer.
18/21
18. Room size - Bigger rooms are lower risk.
19/21
I didn't put these in order based on importance because I don't think you can. It varies and isn't simple. If people are assessing risk based on one single factor (eg. community rates or vax status), they aren't fully assessing risk.
20/21
And when you look at what measures you need to take to reduce the individual risk factors, it leads you to one conclusion - layered approach. Vax + rapid test + mask + air quality + go outdoors...
Did I miss anything?
21/21
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