Thread by @sfrantzman

I am loathe to do this because I am skeptical of the many "instant experts" out there; But when people put up these charts of places like Denmark showing rising Covid cases and then mark them and say "Delta" and "Omicron"...what is this based on? What testing shows each variant?

There are lots of people apparently being tested, or cases reported...but what test do they do that shows each variant? When reports say "this variant is now dominant" or "99% of cases are Delta" or "40% are Omicron"...what is this based on?

Is it sample of cases from hospital...it's not like these home tests, right? So which test is it that media/governments/researchers rely on to determine how widespread a specific "variant" is? It seems just looking at a chart and adding "Omicron" text is easy, but unclear.

I'll add a few examples as sub-tweets, because we see a lot of people tweeting about "Delta is attacking Holland" and "there is a surge of Delta" here or there...how do the people tweeting know to segment each "variant" spread?

So here is one example.

https://twitter.com/kakape/status/1470437771852537856?s=20

And another example;

https://twitter.com/RageSheen/status/1470125914788818944?s=20

Recall that back in Oct-November cases. were very high in Austria, Germany, Holland, France etc; "The Netherlands recorded its highest number of coronavirus cases in a single day on Thursday, with 16,324 people testing positive "- Nov 11.

Austria in late October "Austria on Wednesday recorded more new Covid-19 cases than in any other 24-hour period so far in 2021"

So the "surge" of "Omicron" seems to me to come on the back of what was already a rapidly growing case number across the continent...

So far the only response is that this is "public health data"...and that data spells out the percent of cases of "Omicron"...based on what sample, how is the data created? How does it work, how is it compiled?

So what I understand from this is that they were doing "Delta" PCR tests...now "Variant PCR test results (formerly Delta PCR test results)"...and the data is available here: covid19.ssi.dk/virusvarianter…

And what I understand from the data itself is that on December 10, the most recent, there were 2,912 tests performed of this type and of that 381 identified as "Omicron"...thus 13% of total.

And what I understand is that overall tests in Denmark number some 708,000 in the same week, meaning the the extrapolated data is from like 35,000 PCR tests of the 708,000 total...so this is a snapshot...statista.com/statistics/110…

The answers of course are predictably self-assured without any nuance of saying that what you're seeing is a snapshot of a much larger number of tests, because clarifying that is thought to be too confusing for average people...