Coronavirus (COVID-19) Discussion Thread

[Bofferbrauer2]

numberwang said:

Torillian said:

Where does that article say anything about false positives? PCR tests are extremely accurate and almost never give a false positive to my knowledge so I'd be interested to know where you get the information that up to 5% of results can be false positives. 

I've seen an overview page yesterday about specificity and sensitivity for different PCR tests on the market but I can't find that site right now. The claimed range was 0.2-5% for specificity error (false positives) and typically less for sensitivity error (false negatives). I remember that common corona viruses increase false positives for Covid as well. Anyway what's the point of increased testing if all you get is something so close to nothing?

Netherlands are a more interesting example with a "second wave" of cases created by some real infections and increased testing. We could see a lag of about 1 week between cases and death during the first wave but now we got 4 weeks of second wave with no more deaths. Herd immunity achieved.

You should have a look who's infected in that second wave there. Just like here in Luxembourg, most of the new infectees were under the age of 40, and since we have not just good, but more to the point functional and functioning healthcare systems over here, persons under the age of 50 don't die from the disease.

Increased testing just means you can find asymptomatic patients more easily.

Luxembourg can also actually disprove your theory that the increase just comes from increased testing. We ended the first mass testing campaign on July 7 for the summer break (will resume in mid September), after that the number of daily tests went down substantially from 22k to 7k. Despite this, cases continued to climb and peaked twice, first on July 16 and then again on July 29 with 163 and 158 cases respectively, much higher than the 61 cases we had on July 7 (which still was the highest number of cases we had since April 16 at the time).

Testing has been mostly stable since mid-July but only in August did we see an inversion of the trend and case numbers going down. And this decrease boils down to tighter controls in café/bars and festive sites where the youth partied the end of the lockdown and infected everybody for a second wave, not any change in test numbers.