Safety Turducken

(It's a great title. Just admit it).

This week’s post is a little late, for various reasons, but I hope it will be helpful. I want to address the biggest question of late, for all of us.

THE HOLIDAYS.

How can we see family safely? Should we? What are the actual risks? I’m going to dive in. I should say that on this topic, as often, I found some inspiration and good ideas from Kelly Fradin who you should follow and read.

The Framework

In May, I wrote about the “Five Step” decision-making strategy — question framing, risk mitigation and evaluation, benefit evaluation, deciding. In the case of the holidays, like most decisions, it’s not a bad place to start (I think). However: it has become clear as people have reached out is that people are struggling with the middle steps on risk.

That is: we kind of know the question in most cases — see family in whatever way is the “tradition”, or skip it. And we know the benefits. And we know we need to decide — there is a clear deadline. But what people seem to be craving is both an understanding of how to mitigate risk, and a better sense of the size of the risks.

The more I thought about this, the more I realized the right way to think about risk here may not be far off from the “Safety Lasagna” idea I wrote about a few weeks ago in the case of school. (Later, some people told me this was called the “Swiss Cheese Model” but I do not care for Swiss Cheese so I’m going to ignore that.) There are layers of protection we want to think about around the holidays. Both mitigating and evaluating risks rely on thinking through the layers.

It’s the holidays, though, so let’s skip the lasagna and go with a Turducken. Very broadly, what are the layers?

Layer 1: Limiting chance that the virus enters your holiday gathering.

Layer 2: (Relevant if layer 1 fails): Limiting spread when you are together.

Layer 3: (Relevant if layers 1 and 2 fail): Preventing spread when you return.

Basically, the key to a safe holiday for you — but also for society — is to limit chance you bring the virus, limit chance you spread if you do bring, and limit chance you spread it out if someone does get it. This Layer 3, this is key. I talk a lot about individual risk, and I think that’s important here, but there are also big issues of social risk. We have to try to figure out how to keep the holidays from generating COVID-19 spikes. This is our responsibility.

So let’s dig into this: what goes into the layers, how can they be as safe as possible, and can we say anything about how big the risks really are.

Layer 1: The Chicken

The chicken layer focuses on the risks of the virus getting to your gathering. At the core, the risk is:

Chance someone is infected X Chance the infection gets through whatever barriers you put in place

There is some base rate chance each person is infected, based largely on the rate in the area they are in. And then there are things you can do to lower the risk in the lead up to the holiday.

I know what you are saying: what are those numbers?

What’s the actual chance you’re infected with COVID-19 at a given moment? Lets assume you are an average person in your area, neither especially high or low risk. There are two ways you could evaluate this. First, you could look at case rates in your area. Here’s a nice map. Where I am, here in Rhode Island, we are averaging 12.6 cases per 100,000 people per day over the last week. What does that mean? If we assume that people are infectious for 10 days (this is based on CDC isolation criteria), then that means 126 out of 100,000 people are infectious at any given time, or about 0.12%. So there about a 1.2 in 1000 chance of you having COVID, by this metric.

Of course, not everyone is tested. So case rates are probably low. You could also look at the positivity rate — the share of people tested in your area who test positive. In RI, that’s about 1.5%. That’s likely to be very high, especially in areas with limited testing (if we have no tests, we only test sick people, so this number will be a very high estimate for asymptomatic people).

Bottom line: the number is probably something higher than the case rate but lower than the positivity rate.

Okay, so that’s your base rate (or a range, anyway). If you’re an average person and you do nothing in this chicken layer, that’s the risk of bringing COVID-19 to your family gathering. What can you put in your chicken to lower the risk?

  1. Quarantine/Lockdown. Go out less, do not send kids to school (if they ever go), limited playdates, more like lockdown. This will lower the risk. How much? If you fully locked down for 14 days, let’s say basically this lowers to zero. If you did a week, you’d get about half the impact — half of infections show up within 5 days, so if you are quarantined for a week, you rule out about 50% of infections. If you do just a few days, you get a bit less than that. So let’s say you “lockdown” for a week and you started with a risk of 5 in 1000; now you’re at around 2.5 in 1000.

  2. Testing. If you are going to quarantine for 14 days, there isn’t a lot of reason to test. If you are not, you can imagine testing may pick up some infections. Let’s say you are going to quarantine for 5 days and then test before going. 50% of infection would have shown up already. Let’s say the test picks up 80% of the remainder. A little calculation, and your 2.5 in 1000 risk is down to 0.5 in 1000.

  3. Safe Travel. This is a tricky bit. Flying, driving a long way with stops, these all add something to your risk. I’ve written a bit about this before and my sense is that these risks are really quite small if you do them safely. With the caveat that kids under 2 cannot wear masks, so it’s likely best if they are not the ones traveling.

The way I’ve written it, from the standpoint of Rhode Island, makes the numbers seems small. But if you’re in a place with high and rising rates, these numbers could be an order of magnitude higher — we’d be talking about 5 or 10 in 1000 even with quarantine and testing, which is a much larger risk. (A useful comparison may be flu in terms of prevalence: about 10% of the US population gets the flu in a given year. If we think of the flu season as about 35 weeks, this means a risk of 2.8 per 1000 in each week).

Layer 2: The Duck

Okay, so you’re all together. How can you mitigate risk of spread? Again, we’re back to

Baseline risk of spread X How much lowered by mitigation

Here, you’ve got control over both. If you see your family outside for a hike, that’s low risk and it’s not hard to wear masks to lower it to, basically, zero. If you’re having dinner together, though, or staying in a house together, these risks are higher.

How high? This study in India puts transmission risk for household contacts around 10 or 11%. My sense is this is consistent with other studies (South Korea, etc). Which is to say: if someone shows up with COVID-19 at your holiday, and you all stay together in a house and have close contact, there is a 10% chance they will pass it to you. Part of what is difficult is it’s clear that there is huge variation across individuals in how much they pass it — some people are just really good spreaders — which is to say that it’s likely a lot of people in the house get it or no one.

How can you mitigate this? Honestly, if you are staying together, it will be hard. Which isn’t to say impossible. You can try to limit physical interaction and avoid obvious things like sharing glasses. You can wear masks, but this may be impractical for several days. You can wash your hands a lot and not touch your face. All good ideas and likely to lower the risk.

But the biggest risk lowering activities are going to involve setting up the holiday differently — meeting outside, meeting for a meal only but not staying together, etc. If you can be in a hotel or an AirB&B and see the family in a more distanced way, that is lower risk. Whether or not these are feasible is unclear, and probably depends on your family.

In my view, this intermediate layer is clearly the thinnest. Unlike schools, where there is a lot you can to do mitigate risk while people are there, in-household-family-gathering mitigation is tough. Especially when people are drinking which, let’s face it, they are.

Layer 3: The Turkey

We want to imagine the virus got through Layer 1, and then Layer 2. You or someone in your family returns from the holiday with the virus. This is scary, and obviously your first concern here will be to get better. But this layer is really about a second concern — you return with a mild or asymptomatic case, or one that doesn’t show up for a few days. If you jump back into “normal” life, whatever that is, then the virus can get out of your family into the broader community.

If this happens — and if it happens a lot — we’ll see spikes associated with the holiday. The same way we saw them at the 4th of July, etc. Younger people, mostly, getting together, spreading the virus, not knowing they are sick and spreading it out to others. Investing in this layer is crucial for protecting our communities.

The turkey layer is basically the same as the chicken layer (I know, blasphemy!). Quarantine, possibly testing. The longer you do it, the more benefit. The value depends also on the baseline risk. If you travel to a high prevalence area, especially from a low prevalence one, or to a holiday with a lot of people from areas with outbreaks, your chance of infection is higher.

What does this mean? It depends on your situation. If you’re home, homeschooling your children or with a baby, this mean mean virtually nothing — you’re already pretty isolated. But if your kids are in school or day care, or you are back at work in person, this consideration may suggest more caution in the week after Thanksgiving. And for schools that are in person, this may suggest reason to encourage families who travel for the holidays to spend a few days virtually. I know I’ve argued elsewhere that schools are relatively low risk environments, and I think they are, but it doesn’t mean people can’t come in from outside with the virus, and this will drive the need to quarantine, etc.

Putting it Together

The layers are all about safety and risk, and my suggestion here is you think carefully about what is feasible in terms of mitigation at each step, and then evaluate the overall risk of infection spread. You’re not done, of course, since there are the benefits to consider and also the risk of serious illness if infected. A risk of 2.5 in 1000 looks very different if you have an immune compromised older parent than if everyone is under 60 and healthy.

A Few Specifics

I wanted to address just a few specific questions that people have raised.

  1. My husband’s family refuses masks and will not take any precautions and they make fun of us if we wear masks. They want to all get together for the holiday. Should we go? (It’s me and my husband and our toddler; all healthy). Yikes. But everyone’s family has their stuff, I guess. I’m going to assume for the purposes of this that you basically cannot argue with them productively. Given that, you’ve kind of destroyed layer 1 (at least on their end) and made layer 2 very limited. Yes, you can wear a mask and be made fun of, which is fine, but as I note above this may not be practical anyway and the Duck layer is already pretty thin if you’re planning to stay with them.

    To me, the two key questions here are your own disease risk (which seems like it is low), and the broader spread risk. If you do this, you should do it knowing that there is some chance you’ll get sick, although given your age and so on it is unlikely you’ll be very sick. But I’d also urge you to invest strongly in Layer 3. You can choose to take on personal risk here, but if enough people stop the chain of the virus then you may mitigate the risks to the broader community.

  2. We’d like to be tested but where could we do that? Some states have asymptomatic testing available for travel, so you could seek that out. There are also private market solutions to this, although they are expensive (see here, for example). Cue my usual complaints about the US and testing.

  3. Is 14 days really necessary? I wish we knew more about this. The best data we have suggests nearly all cases (like 98%) show up within 11 days, and all by 14 days. More than half by 5 days. But this is based on a single, fairly small sample. I suspect we’ll learn more about this from Universities which are doing more testing and monitoring, but for now this is the best we have.

A Final Word

For some of you, you’ll do this and you’ll decide, basically, you cannot do Thanksgiving this year. It isn’t feasible, the risk isn’t worth it, or something else. This will be sad. Others will decide to go. Unless you’re an unusual person, or you’ve been able to really mitigate the risks, this will make you anxious.

In my view, it’s important to acknowledge this. Neither of these choices is likely to make you feel the kind of unbridled happiness that the holidays (usually) bring. So take a deep breath, make your Turducken, make a choice and try to move forward.


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