The Most Important Test You’ve Never Heard Of(davidzweig.substack.com)
davidzweig.substack.com
The Most Important Test You’ve Never Heard Of
https://davidzweig.substack.com/p/the-most-important-test-youve-never
7 comments
Furthermore, the author essentially says: "4% is low and can be neglected", but gives no reason why that number is supposed to be low. It reads like gut feeling.
Think about it: you have a room of 100 people, 4 of them might be asymptomatic spreaders. From what we observed during the pandemic, there were super spreader events, where one person infected hundreds of others. 4% doesn’t seem irrelevant.
Think about it: you have a room of 100 people, 4 of them might be asymptomatic spreaders. From what we observed during the pandemic, there were super spreader events, where one person infected hundreds of others. 4% doesn’t seem irrelevant.
Agreed. Also, our understanding at the time was that people were spreading it in the days before developing symptoms. Does the Stanford study adequately sample that population? We have no idea, because this study wasn't designed to answer questions about asymptomatic spread. All they did was run a special PCR test on a convenience sample of people they had lying around in the hospital, and report the results they got from that. Maybe most of those people were post-symptomatic, which would explain why they had a lot of dead virus lying around to be collected in the swabs.
If these findings had revolutionary implications, they could have been surfaced at the time. Other people at Stanford had no issue broadcasting their opinions and getting heard.
If these findings had revolutionary implications, they could have been surfaced at the time. Other people at Stanford had no issue broadcasting their opinions and getting heard.
Not to mention that even standard testing wasn’t scaled up adequately in the time period in question. A better test would’ve been better, but we couldn’t even get the less-good test rolled out at scale in 2020.
It’s irritating to have to rehash these fairly moonshot-in-retrospect ideas when there is ample unambiguous, generally useful low-hanging fruit: hospitals should not run out of PPE; schools & hospitals should have excellent air filtration systems; tests, once developed, should be able to occupy nearly all relevant manufacturing capacity immediately
How can an asymptomatic spreader, that is without sneezing/coughing, effectively infect 100s of people? That’s never made sense to me.
It's about the size of the water droplets needed to transmit the virus.
If big ones are required, you need close contact and/or sneezing/coughing. If smaller droplets are sufficient, other vigorous oral activities like singing or excited close-quarters talking could spread the virus more effectively (choirs and professional conferences were important superspreader events in the early pandemic). Or maybe even just being together for long periods of time in unfavorable ventilation conditions.
In my recollection, epidemiological case studies have suggested that being together in unfavorable ventilation was the biggest risk factor overall. There were papers that looked at people's status, contacts over time, the rooms they were together in, and the ventilation conditions, all in a very detailed way and basically inferred the exact course of transmission between specific individuals.
If big ones are required, you need close contact and/or sneezing/coughing. If smaller droplets are sufficient, other vigorous oral activities like singing or excited close-quarters talking could spread the virus more effectively (choirs and professional conferences were important superspreader events in the early pandemic). Or maybe even just being together for long periods of time in unfavorable ventilation conditions.
In my recollection, epidemiological case studies have suggested that being together in unfavorable ventilation was the biggest risk factor overall. There were papers that looked at people's status, contacts over time, the rooms they were together in, and the ventilation conditions, all in a very detailed way and basically inferred the exact course of transmission between specific individuals.
They just need to infect one superspreader
Forced ventilation might do it.
I think your point still stands, but it's not 4% of the general population. If you have a room of 100 people with asymptomatic COVID, it wouldn't matter if any of them are spreaders; there wouldn't be anyone to spread to. I have no idea how you could determine the prevalence of asymptomatic COVID though.
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I feel like I read a lot of “this research came later and is right” but often it is just two different sets of research with different results and neither addresses the other exactly.
That’s ok as any given research can’t address all other research.
But it’s frustrating to read when presented as we should just disregard some other research…as I don’t know why we would disregard either.
That’s ok as any given research can’t address all other research.
But it’s frustrating to read when presented as we should just disregard some other research…as I don’t know why we would disregard either.
> 1. Can we really sweep away all the evidence of asymptomatic spread because of a "special PCR test" years after the fact? We had a lot of good reasons to believe this at the time, and none of them are engaged with here.
What evidence are you referring to? The article seemingly contradicts this in the following:
> In June 2020, Dr. Maria Van Kerkhove, head of the World Health Organization’s emerging diseases and zoonosis unit, said that transmission from asymptomatic people was “very rare.” This conclusion was based on a number of countries doing very detailed contact tracing, she said
Point #2:
> that means that symptomatic people were going out in public and spreading it.
That is precisely what happened. There were many reports of "outbreaks" that were traced back to very symptomatic people that attended parties or duties and infected large groups.
> either because they did not understand their symptoms or didn't care. So what do you do, other than require masks by default? What does this change?
There were many reasons people did not comply with the directives. Some right, some wrong. Requiring masks, social distancing, etc. for everyone would make sense even if asymptomatic people cannot spread the virus, given that some people are going to ignore their symptoms and expose others. This assuming masks and distancing work, the directives were legal and/or moral, and the virus was not going to get around to everyone eventually anyway and harm the same amount to the same extent.
People lied, ignored, and obfuscated the truth about their symptoms and contributed to the spread of the virus. People also lied, ignored, and obfuscated the truth about the nature of the virus and contributed to bad policy.
What evidence are you referring to? The article seemingly contradicts this in the following:
> In June 2020, Dr. Maria Van Kerkhove, head of the World Health Organization’s emerging diseases and zoonosis unit, said that transmission from asymptomatic people was “very rare.” This conclusion was based on a number of countries doing very detailed contact tracing, she said
Point #2:
> that means that symptomatic people were going out in public and spreading it.
That is precisely what happened. There were many reports of "outbreaks" that were traced back to very symptomatic people that attended parties or duties and infected large groups.
> either because they did not understand their symptoms or didn't care. So what do you do, other than require masks by default? What does this change?
There were many reasons people did not comply with the directives. Some right, some wrong. Requiring masks, social distancing, etc. for everyone would make sense even if asymptomatic people cannot spread the virus, given that some people are going to ignore their symptoms and expose others. This assuming masks and distancing work, the directives were legal and/or moral, and the virus was not going to get around to everyone eventually anyway and harm the same amount to the same extent.
People lied, ignored, and obfuscated the truth about their symptoms and contributed to the spread of the virus. People also lied, ignored, and obfuscated the truth about the nature of the virus and contributed to bad policy.
We're still not being careful about asymptomatic, presymptomatic and paucisymptomatic.
If someone is infected with SARS-CoV-2 and feeling nonspecific aches and pains and doesn't realize they're sick yet, and they only start feeling very ill a day or two later was that person "asymptomatic"?
I can fairly well believe that people who are truly asymptomatic under the strictest definition and never fall ill are very unlikely to transmit the virus.
At the same time people who are going to get sick and are ignoring or in denial about the first symptoms they might be feeling are probably very likely to be walking around transmitting virus.
If someone is infected with SARS-CoV-2 and feeling nonspecific aches and pains and doesn't realize they're sick yet, and they only start feeling very ill a day or two later was that person "asymptomatic"?
I can fairly well believe that people who are truly asymptomatic under the strictest definition and never fall ill are very unlikely to transmit the virus.
At the same time people who are going to get sick and are ignoring or in denial about the first symptoms they might be feeling are probably very likely to be walking around transmitting virus.
What were those reasons?
I mean, knowing the difference between closing schools vs not is already here: Many countries never closed schools, or at least I know mine never did: Sweden.
If there is a marked difference in spread of covid it should be clearly visible in the data. Also we never had a wide mask mandate. It was reguired in super markets and public transport for a while.
If there is a marked difference in spread of covid it should be clearly visible in the data. Also we never had a wide mask mandate. It was reguired in super markets and public transport for a while.
Yet again the importance of a social safety net is underlined. In the US many people send their visibly sick kids to school because they need to go to work and don't have the time off available. If there had been any chance parents would do / would be able to do the right thing of their own volition, we wouldn't have had to close so many schools.
This is not as significant as the author thinks it is, for one reason: a significant number of symptomatic people will (and did) behave as if they were not. The responsible, rational behavior assumed by the author is not realistic.
Interesting that the infectiousness of asymptomatic patients increased markedly during the omicron wave. Perhaps that’s why it was able to spread so quickly.
Yeah: For the majority of the pandemic only 4% of asymptomatic SARS-CoV-2 PCR-positive patients were shown to be infectious. (During the Omicron wave, the percentage peaked at about 25%.)
Also, this:
“The probability of a kid in class who is not sick actually being infectious is very low,” Dr Ralph Tayyar said. Think about it this way: even if every single student in a school without symptoms was infected, 96 percent of them still weren’t capable of transmitting to others. Yet, of course, most people without symptoms are not infected. Moreover, just because 4 percent were technically capable of infecting others does not mean that in actuality they had sufficient amount of replicating virus to do so. We are talking about a subgroup of a subgroup of a subgroup.
Also, this:
“The probability of a kid in class who is not sick actually being infectious is very low,” Dr Ralph Tayyar said. Think about it this way: even if every single student in a school without symptoms was infected, 96 percent of them still weren’t capable of transmitting to others. Yet, of course, most people without symptoms are not infected. Moreover, just because 4 percent were technically capable of infecting others does not mean that in actuality they had sufficient amount of replicating virus to do so. We are talking about a subgroup of a subgroup of a subgroup.
Yep, that 4% to 25% jump is what I was talking about. I’m no virologist but it seems like 6x likelihood of infection would lead to it spreading faster, which of course it did but I don’t know if that was the reason.
It is worth recalling that the early COVID response by the CDC blocked anyone from developing an effective tests then shipped a defective one [0] that seemed to deal a serious blow to the US's earliest response. Whatever the highest standards were for detection, it doesn't seem the US system was on the path to finding it in 2020, there was a lot of bureaucracy to be cut through.
It is all very well to centralise the response, but if the centralised team fails then now everything is bad. Story of centralised power. It was illegal for people to help themselves.
[0] https://www.technologyreview.com/2020/03/05/905484/why-the-c...
It is all very well to centralise the response, but if the centralised team fails then now everything is bad. Story of centralised power. It was illegal for people to help themselves.
[0] https://www.technologyreview.com/2020/03/05/905484/why-the-c...
The article doesn't make any distinction between people who are infected and will never express symptoms and people who are within the incubation period before symptoms onset. Or rather, it seems to only consider the former. I believe pre-symptom infections are much less rare.
Besides, it was well known that PCR tests were not correlated with infectiousness. Michael Mina, an infectious disease expert, has been advocating that rapid antigen tests should rather be used to identify infectiousness.
https://twitter.com/michaelmina_lab/status/16575848737149870...
Besides, it was well known that PCR tests were not correlated with infectiousness. Michael Mina, an infectious disease expert, has been advocating that rapid antigen tests should rather be used to identify infectiousness.
https://twitter.com/michaelmina_lab/status/16575848737149870...
Reading this does bring back this feeling we constantly had during covid, that "its all pointless": The many rules about staying at home when sick, after being, when someone else is sick in the household: All these always felt somewhat arbitrary here in Sweden, and you always knew that you the rules did not guarantee no tranmission, and on top of that there was always the ones without symptoms. Which made all the rigor seems to unneccesary. We abided almost 100% to any rule, but I heard of alot of people who did not.
In the end, I don't think it changed anything, tranmissions till happened and would have happened.
In the end, I don't think it changed anything, tranmissions till happened and would have happened.
Hospitals were overflowing with patients. Millions died because they did not get timely treatment. In countries such as India, there wasn't even enough room to cremate bodies. Home quarantining "flattened the infection curve" enough to make this more manageable. So no, it wasn't all pointless.
In the United States, hospitals were not overflowing with patients and the curve was not flattened. It followed roughly the same curve and wave pattern of the 1918 pandemic. Hospitals were furloughing staff in massive quantities. Ohio tracked and published hospitalization rates and I followed them daily. There was never 100% capacity usage.
Not true for all of the US. In the SF Bay Area, at least, we had 100% occupancy rates for significant periods even after home quarantining was established.
I have been doing some digging and unfortunately cannot find data prior to mid 2020 for most areas. This site https://data.statesmanjournal.com/covid-19-hospital-capacity... has information pertaining to capacity since then, for an incredible amount of hospitals.
Looking at the data for the available time period, I am not able to confirm your statement.
Looking at the data for the available time period, I am not able to confirm your statement.
I don’t see any history in the site. How are you getting history?
The fact that hospitals did run out of capacity in many places in the world is indication enough to me that control measures were important, and hospitals having some capacity is hardly a measure of safety.
The fact that hospitals did run out of capacity in many places in the world is indication enough to me that control measures were important, and hospitals having some capacity is hardly a measure of safety.
In the left column, if you click on the hospital name, it will show the history.
> From a special test they developed, the researchers found a remarkable 96 percent of people who were PCR-positive but without symptoms were not infectious.
> Most people who don’t have symptoms, of course, are not infected. So the likelihood of someone who is not noticeably sick actually being infected and infectious was exceedingly rare. This means that much of the actions we were told—or compelled—to take, including an acceptance of all those closed or half-empty schools, had little to no benefit.
1. Can we really sweep away all the evidence of asymptomatic spread because of a "special PCR test" years after the fact? We had a lot of good reasons to believe this at the time, and none of them are engaged with here.
2. If asymptomatic people rarely spread COVID and it spread anyway, that means that symptomatic people were going out in public and spreading it. Even though they were getting plenty of messaging not to do this. That means that symptomatic people don't cooperate with public health measures enough to slow the spread, either because they did not understand their symptoms or didn't care. So what do you do, other than require masks by default? What does this change?