https://grapevine.is/news/2020/03/15...h-coronavirus/
So they already had 180 known cases (zero deaths). Thats a fair number in a small country (0.05% of their population), but they do like to travel.
They then swabbed volunteers from their population. Found another 7 positive results from 700 swabs (1% positive). That number will firm up with a few thousand more swabs coming back over the next few days.
The true number of people who should have a positive swab will be a bit higher than 1% as swabs miss 20-30% of cases. So maybe they had 10 positives, and the swabs found 7 of them - something like that.
Hence perhaps 1.2% of their population currently could have a positive swab if the swabs were perfect.
Then there is going to be even more people who would have previously had a positive swab a week or two back, but are now negative.
So perhaps 1.5% of the population currently have the virus, or have already cleared the virus.
Playing with the math a bit more (and this is stretching things a bit I accept, we don't know if the 700 swabs are a representative cross section of their society):
Population Iceland = 365,000
They already knew about 180 cases from routine medical care
But there could be another 5,475 unknown cases (1.5% population).
So not that many cases will ever get diagnosed.
Note that half the cases didn't have any symptoms, and the rest thought they had a cold.
Anyway if somewhere like Iceland (small and remote from China) now has something like 1.5% of its asymptomatic / minimally symptomatic population infected, it is going to be way higher than 1% in Australia (and about 100% in Sydney)
This suggests there is a fair chunk of under-water ice with the corona iceberg.