8 ms·

> Cough (7.5%), shortness of breath (1.4%), and fever (0.7%) were all uncommon among COVID-positive individuals It seems the more important point here is that

by jcp2fa 6y ago

> Cough (7.5%), shortness of breath (1.4%), and fever (0.7%) were all uncommon among COVID-positive individuals It seems the more important point here is that the majority of the COVID-positive individuals were asymptomatic, putting another datapoint towards the conclusion that there are orders of magnitude more people that have this disease than have tested positive. We need more studies to gather data on these asymptomatic cases if we want to reopen the economy soon. Imagine if 10+% of the population already had COVID and where immune, we'd be much closer to heard immunity than we currently think.

drtillberg 6y ago
There are several variables here but it's also important to keep in mind that the 36% positive rate in this cohort presumably does not include people who had the virus and recovered.
- gnulinux 6y ago
  A Diamond Princess ex-passenger died as late as March 24. The first patient was tested positive on February 1, and the ship was quarantined on Feb 4, and everyone left the ship on March 1. It doesn't seem unlikely you can die from this virus a month (or even two months?) after testing positive. Or maybe I'm missing something?
  - irishcoffee 6y ago
    Occams Razor would suggest that they may not have caught the virus on the boat then but perhaps after, no?
    - gowld 6y ago
      Why? 23 days for the longest time to succumb isn't surprisingly long. small exposure, healthy person / lucky genes, good medical treatment, but not quite healthy/lucky/good enough.
      - gnulinux 6y ago
        Well the longest possible according to this data would be 54 days. We don't know the identity of patients who died, could be one of the people who tested positive on Feb 1 (or sometime in early Feb).
    - ska 6y ago
      Given current information, Occam's razor cuts the other way. Unless perhaps that person had another known significant contact.
goatsi 6y ago
Or the majority were presymptomatic. They don't give a timeline of how long after the first cases in the cluster were detected that the testing took place, so these individuals might have been in the first week of the infection.
jlmorton 6y ago
We already have lots of data that says this is not true. For instance, on the Diamond Princess, widespread testing of a confined group initially found many asymptomatic infections, but the majority of those turned out to be pre-symptomatic, not asymptomatic. Longer term follow-up found ~25% of infections were asymptomatic. In the US, we're now doing significant amounts of testing, but we're still primarily testing only those with severe symptoms. Even limiting our sample to people presenting with severe matching symptoms of COVID-19, we're finding ~20% PCR-positive for SARS-CoV-2. Beyond that, we also have good evidence that the Basic Reproduction Number is somewhere between 2-3. Given a seeding of cases in mid-to-late January, even without social distancing measures, it would be unlikely to have 10% of the population infected yet.
- onlyrealcuzzo 6y ago
  For reference, ~19% of people get the flu and are asymptomatic. Source: https://www.contagionlive.com/news/asymptomatic-influenza-infection-rates-deserve-more-attention https://www.contagionlive.com/news/asymptomatic-influenza-in... > Study results revealed an overall pooled prevalence for asymptomatic carriers of 19.1% for any type of influenza, 21.0% for influenza A, and 22.7% for influenza A(H1N1). For subclinical carriers, the overall pooled prevalence of was found to be 43.4% for any type of influenza, 42.8% for influenza A, and 39.8% for influenza A(H1N1).
- sauwan 6y ago
  The Diamond Princess likely had a very atypical (older) population than the general population though. The CDC is currently estimating an R0 of 5.7, which has likely been repressed by shelter in place orders. But even if it was only 4 before any interventions, there's still a chance there there are closer to 20M cases in the US rather than the 660,000 now. My point is just that there's still a lot we don't know, and small changes in our understanding could implicate massive changes in the reality on the ground.
  - ksaun 6y ago
    Here is a reference for the R0 = 5.7 estimate: https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article
smallgovt 6y ago
> We need more studies to gather data on these asymptomatic cases if we want to reopen the economy soon. I don't understand what's so hard about measuring population infection rate. Assuming the population infection rate is between 1-10%, we would only need to do around ~500 randomized tests to achieve a 95% confidence interval of +/- 1%. For example, let's say we tested 500 random NYC residents for COVID and found that 10 were positive -- a 2% infection rate. The standard error (binomial approximation) for this sample is 0.6%. So, by doing a mere 500 randomized tests, we have a 95% confidence interval of 0.8%-3.2%. Given that overall population infection rate is so important in planning for re-opening, why are we not doing randomized testing in hotspots like NY on a regular basis? Am I missing something?
- DenisM 6y ago
  False positive rate of some antibody tests is 9%, which makes any effect size below that invisible.
  - deleted 6y ago
    [deleted]
  - duxup 6y ago
    Jebus, 9% false positive ... is that even useful?
    - arcticfox 6y ago
      I mean, it's not great, but imagine if it was so cheap and fast we could test the entire population on a consistent basis. In a hypothetical scenario of 1% of the population actually having COVID and 9% testing false positive, you could ask all 10 positive results to self-quarantine and that'd probably be a pretty effective way of shutting down the virus without asking the whole population to stay home. Once the virus spreads more, it gets even more reasonable. (If it gets crushed more and there are very few cases, it does get a little extreme to call it useful though).
      - 6y ago
credit_guy 6y ago
My bet is that it's much more than 10%. In NYC I think it's at least 20%-30% by now. Obviously, I don't have any more data than what you can find online, but anecdotally, I think one of my sons had it; he most likely got it from his piano teacher who exhibited all the Covid symptoms (fever, dry cough, loss of smell), but was never tested. I think at least myself and my wife got this from him as well; likely his two siblings, but they were completely asymptomatic. Our kids' nanny has Covid now (tested at the hospital), and her son too (he's in ICU). I have other anecdotes, and no, I don't have systematic data, but I believe at least 20%-30% of NYC has had Covid by now. Another point of reference is this: according to [1], a back-of-the-envelope estimate of the number of Covid-infected is 100 times the number of dead. It's about 8000 now in NYC, so about 800k infected. That's about 10% of NYC's population, exactly the number you mentioned. [1] https://www.solipsys.co.uk/new/BackOfTheEnvelopeCOVID19.html?ColinsBlog https://www.solipsys.co.uk/new/BackOfTheEnvelopeCOVID19.html...
- dajohnson89 6y ago
  brooklyn resident here. fwiw (not much), it feels like easily 1/3 of the local people i know got some mild fever symptoms in the same 3-week timespan.
  - TSiege 6y ago
    Also from bk. I'll anecdotally second this sentiment. I even got sick with a terrible cough for 2 weeks in the end of February and lost my sense of smell for 2-3 days. My roommate didn't get sick, but I just spoke to my neighbors and they mentioned similar symptoms the week after me.
  - arcticfox 6y ago
    As a counterpoint, I saw a lot of people supporting the idea (with similar anecdotes) that there was a huge outbreak in California in December before we were even testing for COVID at all. Which was empirically demonstrated to be untrue by the later Seattle Flu Study testing of the viral genome. That said, it's a whole lot more likely that you're right than the December-California-epidemic folks, just saying that that type of anecdotal evidence is fairly easy to come by in the winter.
moneywoes 6y ago
Do a lot of these asymptomatic people end up developing severe symptoms? If so, what does that mean for herd immunity?
Alex3917 6y ago
> Imagine if 10+% of the population already had COVID and where immune By some estimates we need over 80% of the population to get it in order to achieve herd immunity, so if only 10% of the population has it we're not very close at all to this being over.
- tomerico 6y ago
  The first 10% to be infected, are also likely to be the highest spreaders (people in close contact with a high amount of strangers). The effect should hopefully be higher than 10% reduction in the reproduction rate.
- chrisco255 6y ago
  If 10% already have it wouldn't that mean we're only a few weeks away from it fizzling out, given the rapid rate at which it spreads?
IAmEveryone 6y ago
> Imagine if 10+% of the population already had COVID and where immune, we'd be much closer to heard immunity than we currently think. We’d be about 1/7 the way there. Meaning we’d see another 6x current deaths to get through this. That’s not even close to acceptable. And the 10% aren’t realistic, anyway. At least nationally. Assuming nationwide rates of 10%, then scaling up by death numbers, would put infection rates far above 100% in New York.
- MikeAmelung 6y ago
  Why would the rest of the country have the exact same percentage of infected as New York City, the only place in the country where most people don't own cars, and almost everyone takes cramped public transportation. NYC clearly has a MUCH higher infection rate than anywhere else in the country.
  - IAmEveryone 6y ago
    > Why would the rest of the country have the exact same percentage of infected as New York City? I didn't say that. In fact, I said the exact opposite: to get to 10% nationwide while explaining the rather large per capita differences in deaths, you'd need either negative infection rates in some places (say, Alaska), or >100% infection rates in hotspots. Neither is possible.
- dorgo 6y ago
  >That’s not even close to acceptable. Is there a choice?
LatteLazy 6y ago
I'm never clear what asymptomatic means in this context. Does it mean the period for which a patient is infectious before they become symptomatic? Or do some people never become symptomatic? And if it's the second, do they cease to be infectious like symptomatic individuals after a time? Or are they infectious long term (aka carriers)?
- nkohari 6y ago
  Asymptomatic means the person had no symptoms at the time of the test, and possibly never developed symptoms. They could also have been presymptomatic, in which case they subsequently developed symptoms after the test. This study didn't do any follow-ups to differentiate.
  - LatteLazy 6y ago
    >presymptomatic That makes sense and that's a useful word, thanks! I've heard it takes about a week before you get symptoms and then they last for 2 days on average. So even if everyone developed symptoms only 22% of people with the disease would have symptoms on a given day...
jimrandomh 6y ago
It is very important to distinguish asymptomatic (does not have symptoms and will never develop them) from presymptomatic (does not have symptoms yet, because the test caught the infection sufficiently early). The people in this study are mostly presymptomatic, and will develop symptoms later.
ummonk 6y ago
0.2% of nyc has already died from Covid-19. That will probably get to around 0.4% or so. This is a lower bound for lethality of the disease. We also know from contact tracing and mass testing instances that only something like half of cases stay asymptomatic forever. It is likely that the people in this study are either asymptomatic because they no longer have the disease or because they haven’t developed symptoms yet. Also, they might just not be recognizing their symptoms. Even without covid-19, way more than 7.5% of homeless people are typically coughing.

by jcp2fa 6y ago

drtillberg 6y ago

There are several variables here but it's also important to keep in mind that the 36% positive rate in this cohort presumably does not include people who had the virus and recovered.

gnulinux 6y ago
A Diamond Princess ex-passenger died as late as March 24. The first patient was tested positive on February 1, and the ship was quarantined on Feb 4, and everyone left the ship on March 1. It doesn't seem unlikely you can die from this virus a month (or even two months?) after testing positive. Or maybe I'm missing something?
- irishcoffee 6y ago
  Occams Razor would suggest that they may not have caught the virus on the boat then but perhaps after, no?
  - gowld 6y ago
    Why? 23 days for the longest time to succumb isn't surprisingly long. small exposure, healthy person / lucky genes, good medical treatment, but not quite healthy/lucky/good enough.
    - gnulinux 6y ago
      Well the longest possible according to this data would be 54 days. We don't know the identity of patients who died, could be one of the people who tested positive on Feb 1 (or sometime in early Feb).
  - ska 6y ago
    Given current information, Occam's razor cuts the other way. Unless perhaps that person had another known significant contact.

goatsi 6y ago

Or the majority were presymptomatic. They don't give a timeline of how long after the first cases in the cluster were detected that the testing took place, so these individuals might have been in the first week of the infection.

jlmorton 6y ago

We already have lots of data that says this is not true. For instance, on the Diamond Princess, widespread testing of a confined group initially found many asymptomatic infections, but the majority of those turned out to be pre-symptomatic, not asymptomatic. Longer term follow-up found ~25% of infections were asymptomatic. In the US, we're now doing significant amounts of testing, but we're still primarily testing only those with severe symptoms. Even limiting our sample to people presenting with severe matching symptoms of COVID-19, we're finding ~20% PCR-positive for SARS-CoV-2. Beyond that, we also have good evidence that the Basic Reproduction Number is somewhere between 2-3. Given a seeding of cases in mid-to-late January, even without social distancing measures, it would be unlikely to have 10% of the population infected yet.

onlyrealcuzzo 6y ago
For reference, ~19% of people get the flu and are asymptomatic. Source: https://www.contagionlive.com/news/asymptomatic-influenza-infection-rates-deserve-more-attention https://www.contagionlive.com/news/asymptomatic-influenza-in... > Study results revealed an overall pooled prevalence for asymptomatic carriers of 19.1% for any type of influenza, 21.0% for influenza A, and 22.7% for influenza A(H1N1). For subclinical carriers, the overall pooled prevalence of was found to be 43.4% for any type of influenza, 42.8% for influenza A, and 39.8% for influenza A(H1N1).
sauwan 6y ago
The Diamond Princess likely had a very atypical (older) population than the general population though. The CDC is currently estimating an R0 of 5.7, which has likely been repressed by shelter in place orders. But even if it was only 4 before any interventions, there's still a chance there there are closer to 20M cases in the US rather than the 660,000 now. My point is just that there's still a lot we don't know, and small changes in our understanding could implicate massive changes in the reality on the ground.
- ksaun 6y ago
  Here is a reference for the R0 = 5.7 estimate: https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article

smallgovt 6y ago

> We need more studies to gather data on these asymptomatic cases if we want to reopen the economy soon. I don't understand what's so hard about measuring population infection rate. Assuming the population infection rate is between 1-10%, we would only need to do around ~500 randomized tests to achieve a 95% confidence interval of +/- 1%. For example, let's say we tested 500 random NYC residents for COVID and found that 10 were positive -- a 2% infection rate. The standard error (binomial approximation) for this sample is 0.6%. So, by doing a mere 500 randomized tests, we have a 95% confidence interval of 0.8%-3.2%. Given that overall population infection rate is so important in planning for re-opening, why are we not doing randomized testing in hotspots like NY on a regular basis? Am I missing something?

DenisM 6y ago
False positive rate of some antibody tests is 9%, which makes any effect size below that invisible.
- deleted 6y ago
  [deleted]
- duxup 6y ago
  Jebus, 9% false positive ... is that even useful?
  - arcticfox 6y ago
    I mean, it's not great, but imagine if it was so cheap and fast we could test the entire population on a consistent basis. In a hypothetical scenario of 1% of the population actually having COVID and 9% testing false positive, you could ask all 10 positive results to self-quarantine and that'd probably be a pretty effective way of shutting down the virus without asking the whole population to stay home. Once the virus spreads more, it gets even more reasonable. (If it gets crushed more and there are very few cases, it does get a little extreme to call it useful though).
    - 6y ago

credit_guy 6y ago

My bet is that it's much more than 10%. In NYC I think it's at least 20%-30% by now. Obviously, I don't have any more data than what you can find online, but anecdotally, I think one of my sons had it; he most likely got it from his piano teacher who exhibited all the Covid symptoms (fever, dry cough, loss of smell), but was never tested. I think at least myself and my wife got this from him as well; likely his two siblings, but they were completely asymptomatic. Our kids' nanny has Covid now (tested at the hospital), and her son too (he's in ICU). I have other anecdotes, and no, I don't have systematic data, but I believe at least 20%-30% of NYC has had Covid by now. Another point of reference is this: according to [1], a back-of-the-envelope estimate of the number of Covid-infected is 100 times the number of dead. It's about 8000 now in NYC, so about 800k infected. That's about 10% of NYC's population, exactly the number you mentioned. [1] https://www.solipsys.co.uk/new/BackOfTheEnvelopeCOVID19.html?ColinsBlog https://www.solipsys.co.uk/new/BackOfTheEnvelopeCOVID19.html...

dajohnson89 6y ago
brooklyn resident here. fwiw (not much), it feels like easily 1/3 of the local people i know got some mild fever symptoms in the same 3-week timespan.
- TSiege 6y ago
  Also from bk. I'll anecdotally second this sentiment. I even got sick with a terrible cough for 2 weeks in the end of February and lost my sense of smell for 2-3 days. My roommate didn't get sick, but I just spoke to my neighbors and they mentioned similar symptoms the week after me.
- arcticfox 6y ago
  As a counterpoint, I saw a lot of people supporting the idea (with similar anecdotes) that there was a huge outbreak in California in December before we were even testing for COVID at all. Which was empirically demonstrated to be untrue by the later Seattle Flu Study testing of the viral genome. That said, it's a whole lot more likely that you're right than the December-California-epidemic folks, just saying that that type of anecdotal evidence is fairly easy to come by in the winter.

moneywoes 6y ago

Do a lot of these asymptomatic people end up developing severe symptoms? If so, what does that mean for herd immunity?

Alex3917 6y ago

> Imagine if 10+% of the population already had COVID and where immune By some estimates we need over 80% of the population to get it in order to achieve herd immunity, so if only 10% of the population has it we're not very close at all to this being over.

tomerico 6y ago
The first 10% to be infected, are also likely to be the highest spreaders (people in close contact with a high amount of strangers). The effect should hopefully be higher than 10% reduction in the reproduction rate.
chrisco255 6y ago
If 10% already have it wouldn't that mean we're only a few weeks away from it fizzling out, given the rapid rate at which it spreads?

IAmEveryone 6y ago

> Imagine if 10+% of the population already had COVID and where immune, we'd be much closer to heard immunity than we currently think. We’d be about 1/7 the way there. Meaning we’d see another 6x current deaths to get through this. That’s not even close to acceptable. And the 10% aren’t realistic, anyway. At least nationally. Assuming nationwide rates of 10%, then scaling up by death numbers, would put infection rates far above 100% in New York.

MikeAmelung 6y ago
Why would the rest of the country have the exact same percentage of infected as New York City, the only place in the country where most people don't own cars, and almost everyone takes cramped public transportation. NYC clearly has a MUCH higher infection rate than anywhere else in the country.
- IAmEveryone 6y ago
  > Why would the rest of the country have the exact same percentage of infected as New York City? I didn't say that. In fact, I said the exact opposite: to get to 10% nationwide while explaining the rather large per capita differences in deaths, you'd need either negative infection rates in some places (say, Alaska), or >100% infection rates in hotspots. Neither is possible.
dorgo 6y ago
>That’s not even close to acceptable. Is there a choice?

LatteLazy 6y ago

I'm never clear what asymptomatic means in this context. Does it mean the period for which a patient is infectious before they become symptomatic? Or do some people never become symptomatic? And if it's the second, do they cease to be infectious like symptomatic individuals after a time? Or are they infectious long term (aka carriers)?

nkohari 6y ago
Asymptomatic means the person had no symptoms at the time of the test, and possibly never developed symptoms. They could also have been presymptomatic, in which case they subsequently developed symptoms after the test. This study didn't do any follow-ups to differentiate.
- LatteLazy 6y ago
  >presymptomatic That makes sense and that's a useful word, thanks! I've heard it takes about a week before you get symptoms and then they last for 2 days on average. So even if everyone developed symptoms only 22% of people with the disease would have symptoms on a given day...

jimrandomh 6y ago

It is very important to distinguish asymptomatic (does not have symptoms and will never develop them) from presymptomatic (does not have symptoms yet, because the test caught the infection sufficiently early). The people in this study are mostly presymptomatic, and will develop symptoms later.

ummonk 6y ago

0.2% of nyc has already died from Covid-19. That will probably get to around 0.4% or so. This is a lower bound for lethality of the disease. We also know from contact tracing and mass testing instances that only something like half of cases stay asymptomatic forever. It is likely that the people in this study are either asymptomatic because they no longer have the disease or because they haven’t developed symptoms yet. Also, they might just not be recognizing their symptoms. Even without covid-19, way more than 7.5% of homeless people are typically coughing.