My guess is that this is referencing Harvard School of Public Health’s Marc Lipsitch who was quoted projecting this in this article (I think, I’m now paywalled so can’t confirm) somewhat out of context and subsequently defended the range in this podcast.
Dr. Lipsitch is well respected in public health and epidemiology communities, FWIW
Related- possibly first use of immune surveillance: https://www.sciencemag.org/news/2020/02/singapore-claims-first-use-antibody-test-track-coronavirus-infections
If you are in public it seems very important? If you touch something that someone infected coughed on in last 2-9 days and then touch your face that’s a likely infection event. Washing your hand “resets the clock” on the surfaces you’ve touched, but doesn’t protect you if you touch something new.
Its obviously ok to touch your face right after thorough hand cleaning- I practice hand sanitizing before I feel the need to touch my face. I think it is really worth practicing that habit, keeping hand sanitizer on you at all time etc, if you can.
You could also wear latex gloves as a reminder not to touch your face (works for some people)
Added my bio at the bottom of the doc, want to keep the bottom line first and not disrupt the flow for my family and friends, who this doc is primarily geared towards (and already know who I am).
Sure.
This makes sense. To say the obvious, it is sensible for everyone to judge their risk individually and adjust precautions as we have more info. A particularly large factor is your age and comorbid conditions, as well as those of people who you would have the opportunity to infect (who may have higher risk and lower risk tolerance).
I think it is likely enough that most people will consider the risk “very high” at some point before we get a treatment to recommend preparing for that eventuality.
Troubling indeed. My guess is this will not be the only cryptic seed case we discover over the next few weeks, unfortunately.
Yeah 7 days was intended to be a reasonable conservative guess. My actual guess is closer to 5.5. As you point out there are testing artifacts that point in both directions. Within china, test shortages, outside of china, slower testing roll out. I’m not an epi expert but I think the gold standard here would be to do something like time-series immune surveillance, where you randomly sample a large group of people from a pop and test them for an antibody reaction and/ or viral RNA, then do the same at intervals later. My guess is this is challenging because of the number of samples required to detect in most places, but maybe if you did this somewhere like italy you could pull it off (you get the population abundance as well).
Its also the case that this isn’t a fixed number, and you expect it to vary from population to population based on fraction of asymptomatic cases, social distancing, pop density etc. So I’m not sure we’ll get a better number than 2-8 days in the short term, which is disconcerting given how big of a difference it makes to risk forecasts.
I’d love to hear from anyone with more epi expertise!
All good questions. I don’t have great answers, but here are a few things.
The disease CAN burn itself out:
When the density of susceptible individuals is low enough (either because many are recovered and immune or because of social distancing) the disease is predicted to burn out. Google “SIR model” for more info. It is really hard to guess when this will be, obviously. It does look like the social distancing measures taken by China, even after alleged number fudging and diagnostic shortages, made the disease spread much more slowly (and MAYBE would have burned it out if China was completely isolated from the world- very dubious though)
Re extreme individual precautions and the long game
I don’t expect this to blow over in 1-2 months, and I wouldn’t advocate that view to anyone else. The recommendations I made are intended to be risk-reducing in the medium- long term as well as the short term. If you have food stock for 1+ month, then you can choose the safest time to go to the grocery store, or leave your food delivery for 10 days to sanitize, and thereby reduce your risk. Likewise, each time you avoid travel or work from home is reduced risk.
You definitely do want to avoid sheltering in place, only to desperately need food or other supplies later when the risk is higher. But as I said above, having food stocks and taken other precautions means you have more options.
It’s also not the case that you will always be at higher risk if you wait. While the exponential doubling is a good approximation in the short term (and important IMO for people to wrap their heads around), things like safe delivery infrastructure, overall proficiency treating the disease, and availability of medical countermeasures like remdesivir will probably improve in the medium term.
I’m curious what you’re thinking of when you say “adopt measures that can plausibly be sustained for one year or even longer”?
Yeah, its an obvious tension. I’m not sure I can satisfactorily resolve it from the perspective of appealing to authority. My advice is based on first principles and aggregating the thoughts of other people who are primarily thinking from first principles. The first principle argument goes like this:
1. It is very unlikely that this disease will be contained in western countries. The CDC apparently agrees with this for the United States.
2. Medical countermeasures are unlikely to be widely available this year. There is some chance that the virus will struggle to transmit in warm weather but this is not high enough to be comfortable.
3. This means the virus is going to spread. Both models and reference class forecasting against diseases with similar R0 suggest that a large fraction of the population will be infected before treatments arrive, e.g. Harvard School of Public Health’s Marc Lipsitch citing 40-70% of population infected.
4. All of this is uncertain, and maybe we are saved by something we haven’t thought of, but given both the median and upper tail scenarios, it makes sense to be prepared. This is not only good for you but also a prosocial action which will flatten the case curve, reduce load on the hospital system, and protect elderly and vulnerable people in your contacts.
So why haven’t they made recommendations to prepare? Not sure. In the SARS outbreak, I don’t believe CDC made recs to prepare, but this Senior CDC official guy reports in his book to have called his wife during the early part of the outbreak (when it looked really bad) to get enough food to stay home for a few months.
The CDC is also really botching testing by all accounts, including both screwing up the reagents so the test is inconclusive and refusing to test people who pretty obviously have the disease. Not to mention the increasing politicization of the virus as well as what appear to be outright gag-orders on US. public health officials.
My model of the world says that when things get bad enough for the CDC to have the political will to announce needed prep measures, it will be well after the time where it made sense to actually prepare (and may lead to runs on grocery stores etc). I don’t know how the NHS works so maybe you’d expect them to be right on the money?
I should say that this advice is largely directed at folks in the U.S., so haven’t thought through the U.K. situation fully.
That’s probably not satisfying. I wonder, though, if anyone could articulate what the (CDC, NHS etcs) first principles argument is for not taking these largely prosocial steps (with exception of N95 which I tried to emphasize is only for extenuating circumstances) to prepare?
I definitely agree that its not a certainty you will need a food stock.
I think my view is stronger than “it doesn’t necessarily seem harmful to”, though. Chinese cities under quarantine have managed to continue food delivery, but my impression is that this relies on state-organized supply lines and infection control measures (like measuring temperature of food preparer and deliverer) which are harder to imagine being executed well in the U.S. I’ve also seen stories of people starving in their homes, but not from credible sources (and anecdotal besides).
I’ll point out, as I think I did above, that viruses related to this one can survive on surfaces for a long time (1- 9 days, a source). This suggests that without knowledge that your delivery person and food preppers are healthy and/or correctly using PPE, you are taking a risk with each delivery.
My median case is that most people will be glad to have the amount of food I advised. It opens up a lot of risk-reducing options in an event like this.
(Based on feedback I’ve updated the dock to say “at least 1 month”)
This is largely me aggregating numbers from people I respect, and my views are in flux (e.g. above)
That said I think it makes sense on a couple of grounds:
if you are below the age of 40 and/or have a mild case, this is ~enough food to ride out a self quarantine after showing symptoms (recovery time estimates vary widely, but I’ve seen 14-30 days)
This is also enough food to self quarantine for the estimated incubation period (5-14 days, with some reports of 20-25 days) if you think you might have been exposed.
My model is that there may be short-term food shocks as well, e.g. runs on grocery stores after more cases are discovered in the U.S. 1 month seems like probably 4x what you need for one of those.
The way I view a food stock is to minimize the number of trips to high-risk places like grocery stores (as a young, healthy person). For people over 40 I don’t much more food, say 4 months is crazy because it might make more sense to completely self-isolate with higher mortality risk.
As for when it makes sense to start eating stocks instead of grocery shopping or going out, its really hard to say. I personally plan on evaluating each public trip based on the logic of how many people are infected in my area * adjustment for undertesting * number of people who have been to the location I am visiting in the last week * ppe safety likelihood . A lot of magic is happening in the adjustment for undertesting bit. I expect this to mean that I avoid crowded restaurants and grocery stores at peak hours starting nowish. My guess is I will choose to start eating my food stocks and only making rare large restock trips somewhere in the 100s of cases in U.S. but I’m not sure.
Would welcome any other ways to think about this.
Just finished Spy Schools by Golden. I would rank it between 1) and 2). Describes the history of espionage in academic and research circles. Doesn’t emphasize cyber, but is much more up to date than 2)-4) and given how relevant academia is, I found the examples more interesting.
Great post. Thought I might share a few related books I’ve found interesting (in rough order of usefulness according to my memory)- I’m looking for more so please share!
1. Perfect Weapon by Sanger. An account of the history of cyberweapons and cyber espionage by one of the NYT reporters who broke a number of stories on covert cyber programs like Stuxnet. I found it relatively “spin-free” compared to other content in the area and probably at least 1.5x as useful as the next most.
2. The Sword and the Shield by Andrew and Mitrokhin. A detailed history of the KGB based on one of the largest intelligence leaks in history (Mitrokhin worked in the KGB archives for years). A lot of the details were in the weeds, it is very USSR centric, and doesn’t reach modern day, but I found it useful for getting a sense of how information security worked in the pre-digital age.
3. Legacy of Ashes by Wiener. A history of the CIA with a definitive slant towards trying to demonstrate the agency is incompetent (I think examples may be somewhat cherry picked to this end based on 2) and other accounts). Still found helpful for getting a general sense of how the intelligence community does info security.
4. Click Here to Kill Everybody by Schneier. Similar to 1) but with a narrative driven more by the author’s various theses on security and seemingly geared toward a more popular audience. Examples are fairly redundant with 1).
(A couple caveats: I wish I knew better examples than the above and read these rapidly and some time ago. I expect that re-reading deeply would change my portrayal of them/ and/or ranking. )
Thank you for doing this. Has been on my list to look at for a while and am really glad we have numbers to work with.