“Certainly there is some degree of asymptomatic transmissibility,” Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said at a news conference Friday. “It’s still not quite clear exactly what that is. But when people focus on that, I think they take their eye off the real ball, which is the things you do will mitigate against getting infected, no matter whether you are near someone who is asymptomatic or not.”
I think Dr. Fauci has missed the point. It’s one thing for me as an individual to treat everyone around me as if they could be a spreader, and act accordingly. I don’t shut down the economy by washing my hands a lot and staying 6 feet away from people.
But when public officials treat everyone as a spreader and order people to shelter in place, that does shut down the economy. So I think it is important to make an informed decision about whether treating everyone as if they could be spreaders is wise. That is, it would help to be able to know the results of the experiment, or to be able to anticipate the results.
The article goes on to say,
Researchers have posted to the open-access site MedRxiv their own recent studies that used data from the outbreak that suggest people can be infectious sometimes days before they show symptoms of Covid-19. Some reports suggest some carriers never experience any.
But being asymptomatic only makes you dangerous if you can be a spreader. The story gives numbers from one research paper.
. . .early in China’s outbreak, 86% of infections went undetected. The paper also noted that because they were so numerous, stealth infections were the source for roughly 80% of known ones.
This isn’t quite the answer we need, though.
Let C be the event “come in contact with someone with the virus who is asymptomatic.”
Let I be the event “become knowingly infected with the virus.”
What the quoted paragraph gives is the claim that P(C|I)= 80/100. That says that of every 100 people knowingly infected, 80 got the infection from coming in contact with an asymptomatic carrier. What I want to know is P(I|C). Out of 100 people who come in contact with an asymptomatic carrier, how many will become knowingly infected? P(I|C) = P(C|I)*P(I)/P(C).
At first, I thought that there cannot be more asymptomatic carriers than there are people infected, so P(I) has to be greater than than P(C). So if the report is correct, out of every 100 people who come into contact with an asymptomatic carrier, more than 80 will become infected. That would seem to justify a lockdown policy.
But remember the important modifier knowingly infected. If not everyone is tested, then certainly there can be more asymptomatic carriers than there are people knowingly infected. If there are 10 times more, then out of 100 people who come in contact with an asymptomatic carrier, only 8 will themselves become infected, and that might not be enough to justify crippling the economy by telling everyone to shelter in place.
So I still think we need harder data. And yet once again, I make a plea for random testing. Since we know P(I), if we also knew P(C), we could make an intelligent estimate of the key probability, P(I|C). That in turn would help inform public policy decisions that are of huge import.
Thank you Dr Kling – this is very strong! Authorities are shutting down the economy, inflicting several trillion in damage, on uncertain data.
“I think Dr. Fauci has missed the point. It’s one thing for me as an individual to treat everyone around me as if they could be a spreader, and act accordingly. I don’t shut down the economy by washing my hands a lot and staying 6 feet away from people.
But when public officials treat everyone as a spreader and order people to shelter in place, that does shut down the economy. So I think it is important to make an informed decision about whether treating everyone as if they could be spreaders is wise.”
It’s the virus, not the quarantine, that is inflicting this economic damage. Even if you did keep most businesses open, most people would have the sense to avoid them as much as possible right now and most of those businesses would still be devastated.
The immediate problem is that the hospital system is optimized for profitability, not pandemic. That works pretty well most of the time but not in a 100 year flood like this. Without quarantines, and probably even with them, hospitals will be overwhelmed when this pandemic really hits in their area. Deaths from Covid-19 (and some other ailments as well) are likely to go up by many orders magnitude when the hospitals are overwhelmed. That has already happened in other countries.
Reports are that even younger first responders, doctors and nurses are dying at higher rates than expected because they don’t have adequate protective gear, and are likely exposed to higher initial loads of the virus than people catching it out in the community. They are the soldiers on the front lines in this war and most of the conversation I’ve seen here has focussed too much on economic issues and not enough on medical ones like more protection for them as a first priority.
The immediate problem is that the hospital system is optimized for profitability
I thought most hospitals were non-profits.
Yeah, most hospitals are non-profits in the sense that they meet the legal requirements of that category for the non payment of taxes. I can assure you they still strive to make sure income exceeds expenses by as much as possible. And that they are the place where you will find the largest concentration of the most highly compensated people in most communities.
Our community has the newest hospital in the state. It was created by merging two existing hospitals in a brand new building with fewer beds than the total that the two previously had. I spent one night in there last November after being treated for a heart arrhythmia in the E.R. It took them about four hours to find me a bed on an average week night well before this crisis. There is very little excess capacity in this system.
In most places, hospital facilities are subject to “certificate of need” laws. The idea is that it is expensive to do stuff in hospitals but if the capacity exists, physicians (who, after all, are taught to do as much as they can for their patients) will use it. This will make our health care system even more over-priced compared to the rest of the world.
I am 99.9% sure that a long, bureaucratic process was involved in building that new hospital.
Yes, I agree that we need random testing. But we don’t yet have the testing capacity to do random testing in any significant way. If you check over at calculatedriskblog.com, you can see how U.S. testing is ramping up. So far, it appears that U.S. testing is roughly doubling about every 3 days. I’m not sure how sustainable is. If you make a more conservative assumption that testing doubles about every week, then you go from the current roughly 50k daily tests to 1ook in one week, 200k in 2 weeks, 400k in 3 weeks, etc. By my math, we probably need roughly millions of daily tests to begin to adequately test the entire population (including asympomatic people). Looks like that is probably at least a month in the future.
Asymptomatic carriers can still work, they have no symptoms, yet.
Consider the distribution of carriers. What is the probability of acute stress onset relative to day of becoming a carrier? Then add in the distribution of death during the acute stress period.
The best outcome is that we are all carriers, like the flu or common cold and acute symptom treatment, swift and simple, reduces deaths way down. Keep the period of acute stress as infrequent as possible by adding special immunity boosters to our annual flue shot.
Right now, the number one advice is stay away from emergency rooms, that is where it seemed to spread in Italy. Go home, treat it like the flu, call the officials and notify them. In a few days we will know a whole lot more about re-infection rates, better ‘flu treatment’ and social distancing policies. A lot of data is coming fast, computers sorting and displaying and speculating and testing.
I think your result is due to an incorrect C. By the 80% figure, C should actually be
C = having *become infected* from someone with the virus who is asymptomatic.
Your C, which I’ll call C2, is:
C2 = having *come in contact* with someone with the virus who is asymptomatic.
We actually don’t know C2|I. It’s probably close to 100%, in a community where many people have the virus and are not symptomatic. It’s C|I that’s 80%, not C2|I.
In other words: persons who were infected by symptomatic patients probably *also* came in contact with asymptomatic infectees. In such a case, we have no useful information about “coming in contact.”
href=”https://amp.theguardian.com/world/2020/mar/22/coronavirus-australia-ruby-princess-cruise-ship-largest-daily-rise-cases”>Coronavirus in Australia: 26 infections from Ruby Princess contribute to largest daily rise in cases
Behavior modification is the challenge. The Contact Tracing required to cover the previous seven days starting with a beach party with 20K in attendances is daunting. How do you properly self-monitor for symptoms that include fatigue when you are self-medicating recreationally? COVID-19 changes what constitutes a Golden Rule violation.
The Aussies talk of preening galahs and obnoxious hoons. This is non-panic mode. I suspect we will be focused on panic-mode and martial law sooner than anyone imagined.
Stupid autocorrect drives me bonkers! I know, the carpenter always blames his tools.
Coronavirus in Australia: 26 infections from Ruby Princess contribute to largest daily rise in cases
“I don’t shut down the economy by washing my hands a lot and staying 6 feet away from people.”
But 6 feet distance does shut down the economy in most cities. If everyone is in the office, I share a 6 X 6 foot elevator floor with 4 to 10 other people typically. I’m within 6 feet of 3 or 4 people in every meeting. Every coffee shop line violates this. Etc.
But being asymptomatic only makes you dangerous if you can be a spreader. The story gives numbers from one research paper.”
This is confusing me. The quote clearly states that studies suggest people can be infectious days before showing symptoms. This makes them a spreader, does it not? I’m not saying we know this stuff with certainty yet — we don’t — but I still believe there is option value in shutting things down while we learn more about it.
These people potentially spread. If they self isolate they won’t spread the virus. They are dangerous only if they expose others.
But why would asymptomatic people self-isolate? I think what is being debated here is how much of these measures are unnecessary. If the policy is “stay home if you’re sick” but asymptomatic people are contagious, then they don’t know to self-isolate, and it spreads anyway.
“That in turn would help inform public policy decisions that are of huge import.”
Come on Arnold, I think we both know facts have almost nothing to do with public policy during normal business, much less a crisis.
We can’t even test all the people with symptoms let alone random testing of people without symptoms. I work for a healthcare organization in MN that did curbside testing for a few days. We had to shut that down and are now only testing people who are admitted. Not even testing people in the emergency department. They have to be admitted because there is a supply constraint on the materials needed for testing.
The Jack Ma Foundation’s COVID-19 Chinese Consultation Center has published a pdf “Handbook of COVID-19 Prevention and Treatment”. The following section clarifies the confusion over asymptomatic spread [bold added]:
You have to test the crud coughed up from the lungs before you can be sure of a positive result.
I find this approach surprisingly un-Klinglike (un-Klingish?). C and I are abstract, high-level variables that mask an enormous amount of important underlying detail. In that sense they are like the macroeconomic variables often railed against on this blog. It is becoming clear that there are hidden variables that we do not fully understand, like the large number of asymptomatic carriers vs. the four members of a single nuclear family who died in NJ. The diversity of responses to the virus are to C and I what specialization and trade are to macro.