COVID is still here. How to figure out what makes sense.
I know that most people are just done with COVID and are living their lives, accepting that they may get it the way they accept getting colds and flu. But those who are older or have underlying illnesses or live with people who fit those categories need to be a little bit more analytical about this because COVID is still super contagious and the threat of serious illness and the residual effects of it loom large. I would feel terrible if I thought I gave it to someone.
When there is a surge, I mask up in public spaces. Since I live in Southern California I have the good fortune to be able to go to restaurants and bars and stay mostly outside or in well ventilated places. (And I will never get on an airplane unmasked again — I always caught something before and now I am well when I travel. Yippie!)
Anyway, here is UC San Francisco’s Dr. Bob Wachter’s latest tweet thread about how to mitigate your risk which I have often found very informative:
Covid (@UCSF) Chronicles, Day 1013
As we enter Covid Year 3, it’s clear we’ll be in our current predicament for the foreseeable future. This means we all need to find our own method to weigh & mitigate risks. Today I’ll describe my “50% Rule” & how it governs my choices.All of us make risk choices daily, without much thought. What is the chance of rain above which I’ll bring an umbrella? Do I buy flood or earthquake insurance? Do I take a statin for my cholesterol? In making these choices, it’s rare there’s an unambiguously “right” answer.
Instead, we weigh the odds & badness of the thing we’re trying to avoid; how unpleasant, risky, & expensive the mitigation is; & our own risk tolerance. Since the cognitive burden of doing this for myriad choices daily is onerous, we all develop rules of thumb to guide us.
I’m utterly aware that many folks have chosen to resume their pre-Covid lives. In doing so, they’ve decided – in essence – that the burdens of mitigation (be it boosters or masks or avoiding indoor dining) exceed the benefits of preventing Covid, or preventing severe Covid.
I understand this. While I try to encourage my mom (who, since dad died last year, now lives alone in South FL) to wear a mask in crowded indoor spaces, I know that the threat of social isolation is very real, and playing cards & eating with friends is important to her.
So now that mom has had the bivalent booster (which greatly lowers her odds of being hospitalized or dying from a case of Covid), I don’t push her on masking & indoor dining. To her, the burdens of being careful seem higher than the benefits. For her, she may well be right.
As for me, I’ve developed a simple algorithm that balances my desire to live life “normally” with my desire to remain Covid-free. It flexes up & down based on current Covid risk & the joys associated with a given activity. I’ve shared this before in bits and pieces, but today I’ll lay out the whole thing, including my mitigation math. My plan will be to follow these rules until the threat of Covid either goes⬇a lot (perhaps via a new antiviral that lowers the risk of Long Covid to near-zero), or goes⬆a lot (likely via a new variant). (8/25)
To make it easy to remember, I’ve taken advantage of fact that many of our current mitigation strategies lower the odds of getting Covid by ~50% (+/- 10-20%). The numbers are admittedly imprecise but close enough & directionally correct. In applying the 50% rule, I’ll be using a version of the Swiss cheese model (Figure), which posits that no one type of protection is perfect (except for total isolation, which seems unsatisfying), and safety can best be achieved by laying different types of imperfect protection on top of one another. (10/25)
Here are some strategies that lower the risk of Covid by ~50%:
• If you’ve been boosted OR had Covid in the past 2 months
• If everybody at a gathering has tested neg. for Covid w/ a rapid test that day
• If an indoor space has really good ventilation and/or filtering.
I’ll now cite a few basic principles that I use for myself. (For context, I’m 65 and have had 5 vaccine shots, including the bivalent 2.5 mths ago.) Because I’m boosted, I don’t worry that a case of Covid will kill me or land me in hospital – particularly since I’ll take Paxlovid if I get Covid. But I still want to avoid getting Covid since each case carries a ~5% chance of symptomatic Long Covid & a small but real chance of raising long-term odds of death, heart attack, stroke, & dementia. Plus I don’t want to infect others if possible.
With that in mind, here are some of my bedrock principles:
1) I’m OK doing anything outdoors with no mask
2) Even if the risk of Covid falls below my threshold for masking, I’ll likely still wear a KN95 when it seems foolish to take any risk at all (ie, crowded airplanes).
3) While reported local case #’s markedly underestimate true prevalence due to home testing, case # trends are useful & the #’s are easily accessible. Plus, they correlate fairly well to other metrics like wastewater & asymptomatic test positivity rates.
I’ve settled on a case rate of <5-10 cases/100K/day in a community as being low enough that I’m ok with indoor dining or small gatherings without masks. Why? Because <5-10 tends to correlate w/ asymptomatic test positivity rates of <1%, meaning <1 in 100 chance that my food server or fellow poker player has Covid, & thus a <10% chance that in a group of 10 any one person is pos.
Why a range (5-10)? First, these are rough estimates.
Second, my risk tolerance depends partly on how important the activity is to me & whether there’s a viable substitute.For example, if local case rate is <5/100K/day, I’m neutral re: eating indoors vs outdoors. When local rate is 5-10, my strong preference is outdoors, but if outdoors is unavailable or too unpleasant, I’m willing to eat indoors (recognizing that I’m taking a modest risk).
I’ve described my above thinking previously. Now I’ll layer in my 50% Rule – how I factor in mitigation strategies.
Let’s use 10 cases/100K/day as a threshold. If local rate is >10, I ask: are there mitigations I can use to lower the EFFECTIVE rate to below my threshold?Here are some practical examples. Say the local prevalence is 14 cases/100K/d, as it is now in Dallas (find any U.S. county here). I’d feel comfortable hanging out with a group of people indoors and maskless only if everyone tested (which would cut the risk by 50%, lowering the effective rate from 14/100K/d to to 7), though my preference (since it’s still >5) would be to eat outdoors if possible (or add in 1 more layer of protection, ie ventilation).
(Below: 4 city estimates.)
If rate in my local community was 32/100K/d, as it is now in SF (BTW, asymptomatic test pos. rate @UCSFHospitals is 4.5%, meaning 1-in-22 people with no symptoms of Covid is testing pos. – pretty high), I’d only be comfy indoors if we applied TWO 50%-⬇ tactics (ie, group testing PLUS ventilation).
Note that if I was still in my 2-month post-booster window, I’d give myself 1 more 50% credit. Since I’m now outside the window (my boost was early Sept), I won’t count my booster as lowering my chance of Covid, though it’s still markedly lowering my odds of SEVERE Covid.
For my NYC pals (46 cases/100K/day), I’d only be comfy at a crowded indoor party w/ group testing, ventilation (yes, current temp is 27) AND if I was in my 2-month booster (or infection) window. Otherwise, sadly, I’d skip it.
Is this too onerous? I don’t know many folk who find it too onerous to check the weather before deciding how to dress. Likewise, this thinking helps me decide which Covid risks I’m willing to take & how to mitigate them. While “normal” sounds great, to me it’s not too high a price to stay healthy. Happy holidays!Originally tweeted by Bob Wachter (@Bob_Wachter) on December 25, 2022.
The NY Times characterizes people who mask up in public spaces as “holdouts” kind of exotic paranoids who just can’t let go of their fears. Whatever. Around where I live I would guess that about 30% of people are still masked in retail stores, including a lot of the workers. I don’t think people even notice one way or the other.