I find this immensely frustrating There is actually not really any evidence at all that serology surveys are 'flawed' or 'dramatically underestimate' how many people have had COVID-19 Sighpic.twitter.com/Q8yWz2FHgV
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Thing is, the editorial is, well, pretty speculative. They are certainly not making any hard claims here, just raising the potential possibility that serology tests are missing mild/asymptomatic cases of COVID-19pic.twitter.com/9rhxGLoZxo
But even there, I actually disagree with the authors of this editorial quite a bit For example, they cite a study conducted in Luxembourg as evidence that IgA serology tests would pick up more people than the more commonly-used IgGpic.twitter.com/HtclbPwXvd
This sounded odd to me, because I've read that Luxembourg paper - it's in my review - and I couldn't remember it making this argument Because it doesn't, really
In fact, the Luxembourg paper DID find that more people had IgA responses than IgG responses, but this was expected because the IgA test WAS NOT AS GOOD The specificity was VERY low for just IgA, meaning there were many false positivespic.twitter.com/Hc64LUyUsD
In fact, if you correct for test characteristics, you find that the IgA test predicts a seroprevalence of ~1% Not that different after all!
Another study the authors cite as supportive of the idea that seroprevalence studies are missing loads of patients is this Austrian study that found a seroprevalence of 42% in an outbreak locationpic.twitter.com/SmByKNqUwS
The authors of the editorial say that this is a red flag, because other serosurveys of Austria have found lower seroprevalence but used only IgG testing, so it's the IgA tests that are pushing up this number (and therefore many IgG-only studies are wrong)pic.twitter.com/doJEoeC8Cw
Except, this doesn't make any sense whatsoever The seroprevalence in Ischgl was 42% because it was the epicenter of the entire COVID-19 outbreak in Austria and indeed Europe!pic.twitter.com/Y1vN1OonqX
Moreover, if you actually look at the IgA vs IgG positives in the study, you'll see that there are only a tiny fraction (~4%) who are IgA positive but not IgG positive
Completely contradicting the editorial
pic.twitter.com/s1LF2DXFoE
So, the evidence that this editorial cites in favor of its argument appears to completely contradict the main point, which is...not great And yet, reported as fact As I said, sigh
More broadly, we know that the antibody tests for COVID-19 are pretty good, and probably don't miss a huge proportion of people who have actually had the disease https://www.bmj.com/content/370/bmj.m2516 …pic.twitter.com/O5vRLc0yY8
I wrote this up in a rapid response to the article which has now been publishedhttps://www.bmj.com/content/370/bmj.m3364/rapid-responses …
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.