Iceland testing shows less deadly than thought

manonboard

I've recently came across some articles this weekend showing that Iceland has been doing some fantastic level of testing. They seem to have taken the virus seriously from the start. The culture places great emphasis on scientific experts so they behave well with these things.
They've tested 10% of their population at random. They found 50% of those testing positive show no symptoms.

I found it a bright hope. Most other countries are testing people who are getting sick and having symptoms.. so is there hope that this could be a good deal better than previously thought? Of course, its still a terrible affliction for our population, but perhaps not as bad as our testing has shown.
Is our testing indicating worst outcomes since we are using our minimal testing capacity where it is needed most?

I'd love if Devore or another great statistical mind could give me opinions on this.

https://www.marketwatch.com/story/iceland-finds-that-half-its-citizens-with-coronavirus-have-shown-no-symptoms-2020-04-10

Hmmzis

It's similar numbers to what a German case study has found in its preliminary findings (subject to peer review).

https://www.sciencemediacentre.org/expert-reaction-to-unpublished-preliminary-findings-looking-at-the-presence-of-antibodies-to-sars-cov-2-virus-in-residents-of-gangelt-in-germany/

The link has some comments with the possible caveats and some warnings of what the study is asserting.

There was a similar case study done in one of the northern Italian towns but I don't have a link for it now and it wasn't quite random, the Germans picked the households at random.

Beasty

This has been stated repeatedly throughout. Anyone following Covid-19 will have heard that up to 80% may be asymptomatic. It's certainly not "news" and it does not need a particularly "statistical" mind to understand.

Of course, we are still in the early stages of understanding this virus and it may only be after we see possibly second and third "waves" or mutations that we will start to have any proper/full understanding

DeVore

Yeah... I'm not a brilliant statistician, I just like numbers (and have a degree in them ). There's not much here to analyse either.

In some ways its good news if half the people are asymptomatic as we may well be further down the line towards Herd Immunity than we know. In other ways its very bad as they can spread the virus without knowing it (making contact tracing more important and simultaneously much harder to do).

But there are subtlies to consider here... for example:

To The Data!
Pop of 364,134
Roughly 10% tested.
So they've tested 36k people (roughly... the numbers that is, I'm sure they were gentle with the test).

Between 0.3% and 0.8% have tested positive (I have no idea why this isnt exactly known!). So lets say 0.5%
So about 183 people have tested positive. With half (92) showing no symptoms.

92 is not a huge number to predict off of. I mean, its good that they are doing random testing but I wouldnt want to say anything dramatic about the global population off of 92 Icelanders.

<snip piece on False Positives and False Negatives because I need to write something better.>