Nearly a third of blood samples taken in Chelsea show exposure to coronavirus • Hacker News Board

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#71

Post by subroutine » Tue, Apr 21, 2020, 1:57 AM UTC

notforever wrote: post #57

subroutine wrote: post #46

Earlier quoted context omitted.

Or you could flip that around and make testing so plentiful everyone is tested 3x (perhaps by independent labs), so the FP rate is more like... 1/10 * 1/10 * 1/10 (1/1000)

No good reason for test errors to be uncorrelated, ie. quite possible same people who trigger false positives on the first test would be false positives on the second etc.

Sure, there will probably be some correlation. Depends heavily on how the 3x testing is designed.

T1. Drive up saliva swab by nurse, for serology test.

T2. Re-deploy census peeps to get samples (and census info) from entire neighborhoods.

T3. 23andMe-like home kit express mail to lab

The odds of people getting a FP on all three might not be 1 in 1000, but it probably isn't 1 in 10.

Anyway, as it is, leading 1 in 10 people to falsely believe they are immune, isn't much better than having no test at all.

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#72

Post by subroutine » Tue, Apr 21, 2020, 2:10 AM UTC

zucker42 wrote: post #58

subroutine wrote: post #46

Earlier quoted context omitted.

Or you could flip that around and make testing so plentiful everyone is tested 3x (perhaps by independent labs), so the FP rate is more like... 1/10 * 1/10 * 1/10 (1/1000)

Assuming false positives aren't correlated even with independently manufactured tests seems like a terrible idea to me, knowing little about medicine.

Sounds like you had a bad experience once, with 'double checking'.

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#73

Post by pmoriarty » Tue, Apr 21, 2020, 4:38 AM UTC

hinkley wrote: post #26

bitcurious wrote: post #19

Earlier quoted context omitted.

Out, about, and willing to speak to a stranger, which I think is the biggest bias. Pretty much everyone I know goes on the occasional walk, but we all stay the fuck away from other people.

My Hollywood movie plot theory is that Covid affects inhibitions.

You might enjoy David Cronenberg's film Rabid.

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#74

Post by DeonPenny » Tue, Apr 21, 2020, 4:53 AM UTC

Retric wrote: post #38

DeonPenny wrote: post #30

Earlier quoted context omitted.

Your never going to have a completely random test. Your randomness comes from you picking for an area and the people who chose to do the test. Saying otherwise is being pedantic to your detriment.

It’s normal to randomly sample multiple locations. Random samples from even 10 random locations are much more useful.

Not if you are trying to figure out the best decision for a specific city/state

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#75

Post by dang » Tue, Apr 21, 2020, 5:14 AM UTC

acchow wrote: post #27

Can we change the title? Article title is "Nearly a third of 200 blood samples taken in Chelsea show exposure to coronavirus" The sample is clearly not random

Ok, changed now. Submitted title was '30% of random sample test positive for Covid antibodies in Massachusetts'

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#76

Post by Retric » Tue, Apr 21, 2020, 3:05 PM UTC

spion wrote: post #48

arenaninja wrote: post #33

Earlier quoted context omitted.

Yep.. I saw a similar headline claiming LA infections are 55x the reported rate. I think the math is likely simpler, and the infection is somewhere between 3x-5x (10x tops). I've read a few reports saying about 50% of people are asymptomatic, 30% show symptoms that aren't bad enough for hospitalization and 20% require hospitalization. I can't find the source I got it from but I believe it was a Chinese study

Based on several studies using different methods, the death rate (infection fatality rate, or IFR) is likely around 0.5% So if you go back the average time from infection to death (2-3 weeks) you can get a sense what the ratio was in your area back then. [1]: https://mothership.sg/2020/03/iceland-covid-19/ (I did the work on the side, extrapolated to about 0.2%-0.5%) [2]: https://www.land.nrw/sites/default/files/asse…

Dimond Princess had 14 deaths out of ~700 infected or a 2% fatality rate though that number has slowly climbed over time. As they tested everyone initially finding a large number of asymptotic cases that’s likely extremely accurate.

The difference is the population was more heathy than the general population, and while older on average, it had a lower percentage of people 95+ years old.

Re: Nearly a third of blood samples taken in Chelsea show exposure to coronavirus

#77

Post by fapjacks » Thu, Apr 23, 2020, 6:36 AM UTC

jfnixon wrote: post #70

fapjacks wrote: post #67

Earlier quoted context omitted.

That antibody timeline was an estimate derived from data obtained from the "original" SARS virus, but it isn't accurate with the SARS-CoV-2 virus. IgM antibodies are present within hours of the onset of symptoms, and IgG antibodies after a few days.

Source?

Sure, find any manufacturer of rapid antibody test kits and look at their documentation for a nice trailhead into plenty of literature about antibody response times with this virus.