I’ve spent some time thinking about endgames here. (Not that I feel like I’ve come to any conclusions. I wish I knew what e.g. the WHO thought the endgame was.) The biggest problem I see with this idea is the lag between input and output—when you change your quarantine measures, you can’t observe the result for at least the 5-7 days it takes the newly infected to get symptoms, and longer if you want to get a lot of confidence in your measurement, over the noise inherent in the system.
Control systems with high lag like this are incredibly difficult to work with. Especially in the presence of exponential growth like this system has—if you accidentally let R get a bit too high, it will be a week or two before you notice, and in that time you will have seeded a ton of cases that you will have to track down and deal with.
I think the most hopeful endgame here, near-mid-term, is that we find a combination of antivirals with high effectiveness against COVID-19, which reduces the rate of severe pneumonia dramatically. At that point our hardest constraint, ventilators, will get relaxed. Beds are a lot easier to deal with a shortage of.
Mid-long-term, of course, we’re all hoping for a vaccine. Who knows whether that’s going to happen.
In Singapore, and China-outside-Hubei, my impression is that very aggressive high-bandwidth contact tracing is working effectively. Unfortunately, at least Seattle has already given up on that, as far as I can tell. But if we can simultaneously raise our ability to do contact tracing effectively, and lower the value of R below 1 until we get the number of cases under some kind of control, we ought to be able to use a combination of contact tracing and more moderate measures to keep it there. I hope.
Of course, the organization primarily responsible for contact tracing in the US is currently rather indisposed. But in theory, the states should be just as able to do it, although some scaling up may be in order.
Control systems with high lag like this are incredibly difficult to work with. Especially in the presence of exponential growth like this system has—if you accidentally let R get a bit too high, it will be a week or two before you notice, and in that time you will have seeded a ton of cases that you will have to track down and deal with.
This is why you need to have borders on multiple scales and cancellation of large events.
If one case slips through, in a week or two they will infect a handful of new people. If you have set up a system of regional and national borders, as well as cancelled large events, you will find out about this trace the contacts and temporarily increase the strength of the lockdown in only that region.
This strategy nearly worked in South Korea, but then patient 31 was a superspreader:
I’ve spent some time thinking about endgames here. (Not that I feel like I’ve come to any conclusions. I wish I knew what e.g. the WHO thought the endgame was.) The biggest problem I see with this idea is the lag between input and output—when you change your quarantine measures, you can’t observe the result for at least the 5-7 days it takes the newly infected to get symptoms, and longer if you want to get a lot of confidence in your measurement, over the noise inherent in the system.
Control systems with high lag like this are incredibly difficult to work with. Especially in the presence of exponential growth like this system has—if you accidentally let R get a bit too high, it will be a week or two before you notice, and in that time you will have seeded a ton of cases that you will have to track down and deal with.
I think the most hopeful endgame here, near-mid-term, is that we find a combination of antivirals with high effectiveness against COVID-19, which reduces the rate of severe pneumonia dramatically. At that point our hardest constraint, ventilators, will get relaxed. Beds are a lot easier to deal with a shortage of.
Mid-long-term, of course, we’re all hoping for a vaccine. Who knows whether that’s going to happen.
In Singapore, and China-outside-Hubei, my impression is that very aggressive high-bandwidth contact tracing is working effectively. Unfortunately, at least Seattle has already given up on that, as far as I can tell. But if we can simultaneously raise our ability to do contact tracing effectively, and lower the value of R below 1 until we get the number of cases under some kind of control, we ought to be able to use a combination of contact tracing and more moderate measures to keep it there. I hope.
Of course, the organization primarily responsible for contact tracing in the US is currently rather indisposed. But in theory, the states should be just as able to do it, although some scaling up may be in order.
This is why you need to have borders on multiple scales and cancellation of large events.
If one case slips through, in a week or two they will infect a handful of new people. If you have set up a system of regional and national borders, as well as cancelled large events, you will find out about this trace the contacts and temporarily increase the strength of the lockdown in only that region.
This strategy nearly worked in South Korea, but then patient 31 was a superspreader:
https://graphics.reuters.com/CHINA-HEALTH-SOUTHKOREA-CLUSTERS/0100B5G33SB/index.html