05-14-2020, 07:13 PM
It appears the test was "Orient Gene IgM/IgG, de la empresa Zhejiang Orient Gene Biotech " .
This particular test does not seem to appear in the 3 evaluation surveys that I've seen (1, 2, 3)
The manufacturer's claims of 87.9% sensitivity for IgM and 97.2% for IgG and 100% specificity for IgG and IgM.
However, those numbers were based on 87/99 and 35/36 tests for sensitivity; 14/14 and 14/14 tests for specificity. (Hmmm.... Do you think they first tried just 36 tests for IgM sensitivity, didn't like the numbers, and tried more? For a company selling >100K units to Spain, that number of tests seems silly small.)
The article also states "In reliability studies carried out for ENE-Covid19, a sensitivity of 73% and 79% respectively was reported for IgM or IgG, and a sensitivity of 85% considering positivity in any of the isotypes, with a specificity of 98% for IgM and 100% for IgG.")
The article reports (via Google Translate)
Any one know why one band would be harder to read (visually) than the other? Does this make sense? Or maybe "read" was more general (such as following the test procedure properly or something like that).
BC, as I don't read Spanish and am having to use Google Translate, did you see whether the numbers presented are raw numbers of positive tests? Or are they adjusted according to the sensitivity/specificity of the test? Did they adjust for age and gender differences?
If they are only using IgG, and the 79% sensitivity is a better measure than 97%, then the true number of positive results should be 26.6% greater (adjusting for sensitivity), driving the (currently undercounted) IFR downward. (Deaths in the last 24hrs = 0.8% of total deaths. New cases = 0.22% of total cases. So each week adds 5% if it were to stay steady. BTW, Spain deaths =~ NYC deaths but Spain cases =~ 1.4x NYC cases)
Of course, COVID-19 IFR calculated across a wide range of ages is highly dependent on the distribution of those ages in the population (the distribution of ages in the sample seems less important). It would seem better to calculate an infection rate (which seems to be reasonably constant at least for most adult-aged people), and then say the IFR for 80+ is X%, for 70-79 is Y%, etc. or for diabetics, Z%
This particular test does not seem to appear in the 3 evaluation surveys that I've seen (1, 2, 3)
The manufacturer's claims of 87.9% sensitivity for IgM and 97.2% for IgG and 100% specificity for IgG and IgM.
However, those numbers were based on 87/99 and 35/36 tests for sensitivity; 14/14 and 14/14 tests for specificity. (Hmmm.... Do you think they first tried just 36 tests for IgM sensitivity, didn't like the numbers, and tried more? For a company selling >100K units to Spain, that number of tests seems silly small.)
The article also states "In reliability studies carried out for ENE-Covid19, a sensitivity of 73% and 79% respectively was reported for IgM or IgG, and a sensitivity of 85% considering positivity in any of the isotypes, with a specificity of 98% for IgM and 100% for IgG.")
The article reports (via Google Translate)
Quote:During the development of the field work, the greater difficulty of reading that the IgM band presents has been revealed, which we believe has produced greater variability in the interpretation of said band between the different geographical units. For this reason, all the results presented refer to the reading of the IgG band of the rapid test. The specific results referring to total positivity (IgG + or IgM +) are presented in an annex.
Any one know why one band would be harder to read (visually) than the other? Does this make sense? Or maybe "read" was more general (such as following the test procedure properly or something like that).
BC, as I don't read Spanish and am having to use Google Translate, did you see whether the numbers presented are raw numbers of positive tests? Or are they adjusted according to the sensitivity/specificity of the test? Did they adjust for age and gender differences?
If they are only using IgG, and the 79% sensitivity is a better measure than 97%, then the true number of positive results should be 26.6% greater (adjusting for sensitivity), driving the (currently undercounted) IFR downward. (Deaths in the last 24hrs = 0.8% of total deaths. New cases = 0.22% of total cases. So each week adds 5% if it were to stay steady. BTW, Spain deaths =~ NYC deaths but Spain cases =~ 1.4x NYC cases)
Of course, COVID-19 IFR calculated across a wide range of ages is highly dependent on the distribution of those ages in the population (the distribution of ages in the sample seems less important). It would seem better to calculate an infection rate (which seems to be reasonably constant at least for most adult-aged people), and then say the IFR for 80+ is X%, for 70-79 is Y%, etc. or for diabetics, Z%