4 ms·

How does this reconcile with the actual data we have on total infection rate in e.g. Spain where a representative poll was done?

osullip 6y ago
Or Australia where about 10% of the population has been tested. https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/coronavirus-covid-19-current-situation-and-case-numbers https://www.health.gov.au/news/health-alerts/novel-coronavir...
christkv 6y ago
We now know a significant amount of people have no symptoms or very light symptoms and no antibody response. An anecdote. My friend and his wife got tested when giving birth. She was positive for antibodies he was not. It is quite possible that for ever person who had antibodies there is some unknown x of people who got it and never developed antibodies.
- cm2187 6y ago
  I have seen Dr Raoult in France suggesting there was likely significant cross immunity from other coronaviruses. If it is the case, would the person develop covid19-specific antibodies after getting it?
- cube2222 6y ago
  IANAD, but you can have similar antibodies (which test positive) from previous infections with similar coronaviruses, not this one specifically. So somebody who had no exposure to COVID-19 could test positive. Afaik that's the main drawback of the antibody test.
  - koheripbal 6y ago
    The antibody test specifically tests for a protein that only exists on covid-19. A positive test result is much more reliable than a negative result.
- baddox 6y ago
  What is the actual effect on the world if that’s true? I’m assuming that people who were infected but never developed symptoms or antibodies were still able to infect other people who might develop symptoms and antibodies.
- peteretep 6y ago
  How would you end up without antibodies? The virus just failed to replicate in your system and died out of its own accord? Or are we suggesting the people with no symptoms are still asymptomic carriers?
  - carey 6y ago
    You will only get detectable antibodies if the virus activated the adaptive immune system. This could be the case if the infection was successfully and quickly controlled by the innate immune system.
  - koheripbal 6y ago
    It doesnt mean thee are no antibodies It means the antibody test doesnt test the right protein.
- legulere 6y ago
  People without symptoms are also much less likely to spread. So likely your friend really didn’t get infected.
- jonathanstrange 6y ago
  How would we know that if they don't even have an antibody response? You're resorting to anecdotal evidence but there is no way to confirm this hypothesis empirically on a large scale. I guess it depends on what you mean by "significant amount", though.
- the-rc 6y ago
  Another anecdote from NY. I had mild symptoms in mid March that didn't exactly match what was being described in the press. Spending hours at the hospital trying to get tested seemed riskier, so I was never diagnosed. In late April I got tested at Mount Sinai hospital for antibodies as part of their study and I was positive, with a high titer. A friend of mine was, too, with a low titer. In a second test two weeks ago I still had the same titer, while she was negative. As an additional anecdote, without mention of other variables, the nurse taking the second sample told me that males had a higher titer on average. I think we also have higher mortality rates, though.
planetmechanic 6y ago
It works well: from the article, "In New York, for example, the researchers’ model suggested that at least 9% of the state’s entire population was infected by the end of March. After the state conducted antibody testing on 3,000 residents, they found a 13.9% infection rate, or 2.7 million New Yorkers."
jjjensen90 6y ago
Because it's possible that there are many, many infected who don't seroconvert or ever manifest symptoms, and therefore would not have been tested with a PCR test, and would have a negative antibody test. We can see this in effect in studies of household attack rates and seroconversion. See this recent preprint and interesting thread (/r/covid19 is a strict science sub, not to be confused with /r/coronavirus) https://www.reddit.com/r/COVID19/comments/hdxwf5/intrafamilial_exposure_to_sarscov2_induces/ https://www.reddit.com/r/COVID19/comments/hdxwf5/intrafamili...
- jakeogh 6y ago
  Excellent. un-nerfed link: https://old.reddit.com/r/COVID19/comments/hdxwf5/intrafamilial_exposure_to_sarscov2_induces/ https://old.reddit.com/r/COVID19/comments/hdxwf5/intrafamili...
- arrrg 6y ago
  But does this get us a lot? In Brooklyn and Queens between 0.2 and 0.25 percent of the total population (!) died. So this sort of puts a floor on the IFR and 0.2 is not that far off from the IFR determined through serological testing – maybe a half or a third of that. So yeah, maybe there is an effect – but can it really be a drastic effect? I don’t think there are orders of magnitude of difference in there, maybe a difference of a few percent (e.g. an IFR of 0.45 instead of 0.5 percent)? My working hypothesis has been an IFR of around 0.5% for a pretty long time, which seems pretty realistic to me.
  - grey-area 6y ago
    But looking at NYC now, after peaking in April, infections and deaths are way down and stabilised, in spite of rising infections in surrounding areas and very few travel restrictions. So something is going on that we don't understand, and it could have a significant impact. If we have a higher immune population than we think, NYC might have passed the worst, if not millions will die in a second wave (though there are no signs of that yet). So this does matter.
    - 6y ago
Hermel 6y ago
The usual tests (including the anti-body tests) only detect the more severe cases.

osullip 6y ago

Or Australia where about 10% of the population has been tested. https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/coronavirus-covid-19-current-situation-and-case-numbers https://www.health.gov.au/news/health-alerts/novel-coronavir...

christkv 6y ago

We now know a significant amount of people have no symptoms or very light symptoms and no antibody response. An anecdote. My friend and his wife got tested when giving birth. She was positive for antibodies he was not. It is quite possible that for ever person who had antibodies there is some unknown x of people who got it and never developed antibodies.

cm2187 6y ago
I have seen Dr Raoult in France suggesting there was likely significant cross immunity from other coronaviruses. If it is the case, would the person develop covid19-specific antibodies after getting it?
cube2222 6y ago
IANAD, but you can have similar antibodies (which test positive) from previous infections with similar coronaviruses, not this one specifically. So somebody who had no exposure to COVID-19 could test positive. Afaik that's the main drawback of the antibody test.
- koheripbal 6y ago
  The antibody test specifically tests for a protein that only exists on covid-19. A positive test result is much more reliable than a negative result.
baddox 6y ago
What is the actual effect on the world if that’s true? I’m assuming that people who were infected but never developed symptoms or antibodies were still able to infect other people who might develop symptoms and antibodies.
peteretep 6y ago
How would you end up without antibodies? The virus just failed to replicate in your system and died out of its own accord? Or are we suggesting the people with no symptoms are still asymptomic carriers?
- carey 6y ago
  You will only get detectable antibodies if the virus activated the adaptive immune system. This could be the case if the infection was successfully and quickly controlled by the innate immune system.
- koheripbal 6y ago
  It doesnt mean thee are no antibodies It means the antibody test doesnt test the right protein.
legulere 6y ago
People without symptoms are also much less likely to spread. So likely your friend really didn’t get infected.
jonathanstrange 6y ago
How would we know that if they don't even have an antibody response? You're resorting to anecdotal evidence but there is no way to confirm this hypothesis empirically on a large scale. I guess it depends on what you mean by "significant amount", though.
the-rc 6y ago
Another anecdote from NY. I had mild symptoms in mid March that didn't exactly match what was being described in the press. Spending hours at the hospital trying to get tested seemed riskier, so I was never diagnosed. In late April I got tested at Mount Sinai hospital for antibodies as part of their study and I was positive, with a high titer. A friend of mine was, too, with a low titer. In a second test two weeks ago I still had the same titer, while she was negative. As an additional anecdote, without mention of other variables, the nurse taking the second sample told me that males had a higher titer on average. I think we also have higher mortality rates, though.

planetmechanic 6y ago

It works well: from the article, "In New York, for example, the researchers’ model suggested that at least 9% of the state’s entire population was infected by the end of March. After the state conducted antibody testing on 3,000 residents, they found a 13.9% infection rate, or 2.7 million New Yorkers."

jjjensen90 6y ago

Because it's possible that there are many, many infected who don't seroconvert or ever manifest symptoms, and therefore would not have been tested with a PCR test, and would have a negative antibody test. We can see this in effect in studies of household attack rates and seroconversion. See this recent preprint and interesting thread (/r/covid19 is a strict science sub, not to be confused with /r/coronavirus) https://www.reddit.com/r/COVID19/comments/hdxwf5/intrafamilial_exposure_to_sarscov2_induces/ https://www.reddit.com/r/COVID19/comments/hdxwf5/intrafamili...

jakeogh 6y ago
Excellent. un-nerfed link: https://old.reddit.com/r/COVID19/comments/hdxwf5/intrafamilial_exposure_to_sarscov2_induces/ https://old.reddit.com/r/COVID19/comments/hdxwf5/intrafamili...
arrrg 6y ago
But does this get us a lot? In Brooklyn and Queens between 0.2 and 0.25 percent of the total population (!) died. So this sort of puts a floor on the IFR and 0.2 is not that far off from the IFR determined through serological testing – maybe a half or a third of that. So yeah, maybe there is an effect – but can it really be a drastic effect? I don’t think there are orders of magnitude of difference in there, maybe a difference of a few percent (e.g. an IFR of 0.45 instead of 0.5 percent)? My working hypothesis has been an IFR of around 0.5% for a pretty long time, which seems pretty realistic to me.
- grey-area 6y ago
  But looking at NYC now, after peaking in April, infections and deaths are way down and stabilised, in spite of rising infections in surrounding areas and very few travel restrictions. So something is going on that we don't understand, and it could have a significant impact. If we have a higher immune population than we think, NYC might have passed the worst, if not millions will die in a second wave (though there are no signs of that yet). So this does matter.
  - 6y ago

Hermel 6y ago

The usual tests (including the anti-body tests) only detect the more severe cases.