4 ms·

The Most Important Test You’ve Never Heard Of

23 points by graderjs 3y ago

WantonQuantum 3y ago
Interesting that the infectiousness of asymptomatic patients increased markedly during the omicron wave. Perhaps that’s why it was able to spread so quickly.
- graderjs 3y ago
  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.
  - WantonQuantum 3y ago
    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.
civilized 3y ago
> Now, a paper from researchers at Stanford University School of Medicine and Stanford Hospitals, raises an extraordinary prospect: transmission from asymptomatic people is far, far less common than we were led to believe. > 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?
- WA 3y ago
  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.
  - civilized 3y ago
    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.
    - ethanbond 3y ago
      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
  - tourmalinetaco 3y ago
    How can an asymptomatic spreader, that is without sneezing/coughing, effectively infect 100s of people? That’s never made sense to me.
sandos 3y ago
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.
- alocasia-1 3y ago
  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.
sandos 3y ago
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.
- the__prestige 3y ago
  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.
  - ghastmaster 3y ago
    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.
    - the__prestige 3y ago
      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.
      - ghastmaster 3y ago
        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/california/06/san-francisco-county/06075/ 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.
mannykannot 3y ago
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.
roenxi 3y ago
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-cdc-botched-its-coronavirus-testing/ https://www.technologyreview.com/2020/03/05/905484/why-the-c...
FranklinMaillot 3y ago
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/1657584873714987009 https://twitter.com/michaelmina_lab/status/16575848737149870...

23 points by graderjs 3y ago

Interesting that the infectiousness of asymptomatic patients increased markedly during the omicron wave. Perhaps that’s why it was able to spread so quickly.

graderjs 3y ago
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.
- WantonQuantum 3y ago
  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.

civilized 3y ago

> Now, a paper from researchers at Stanford University School of Medicine and Stanford Hospitals, raises an extraordinary prospect: transmission from asymptomatic people is far, far less common than we were led to believe. > 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?

WA 3y ago
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.
- civilized 3y ago
  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.
  - ethanbond 3y ago
    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
- tourmalinetaco 3y ago
  How can an asymptomatic spreader, that is without sneezing/coughing, effectively infect 100s of people? That’s never made sense to me.

sandos 3y ago

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.

alocasia-1 3y ago
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.

sandos 3y ago

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.

the__prestige 3y ago
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.
- ghastmaster 3y ago
  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.
  - the__prestige 3y ago
    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.
    - ghastmaster 3y ago
      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/california/06/san-francisco-county/06075/ 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.

mannykannot 3y ago

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.

roenxi 3y ago

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-cdc-botched-its-coronavirus-testing/ https://www.technologyreview.com/2020/03/05/905484/why-the-c...

FranklinMaillot 3y ago

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/1657584873714987009 https://twitter.com/michaelmina_lab/status/16575848737149870...