Heh, the delta is likely because: (1) Iceland has had 6 deaths so it's way, way too early to draw any conclusions from Iceland and (2) everyone onboard the Diamond Princess was onboard a cruise ship, and cruises tend to skew old. The median age of passengers was 69. That age group is affected ~100X harder than young folks (9% CFR vs 0.1% CFR) [1]. If you've got more data to back 0.7% please do share but I've found none compelling so far.
Although for what it's worth Iceland is showing 6 deaths and 1600 confirmed cases for a fatality rate of --- wait for it --- 0.35%.
That paper would give about 3% for a 70 year old. But remember that cruise passengers are healthy enough to be on cruises. 1.5% death rate seems about reasonable when you correct for that (again, this is where you might see that 2x difference).
Iceland has a considerable number of unresovled cases. Whether you use 7 deaths out of 751 recovered, or 20% hospitalization death rate, you get somewhere on the order of 0.9% CFR.
This is all case data, not population studies. The Gangelt study is different because they tested the entire population and not just people walking into hospitals. They found the CFR in Germany (2%) was roughly 10X higher than the actual mortality rate in town.
The CFR is always going to suffer from adverse selection bias at this stage because they're only including people sick enough to walk into a hospital, and not folks who were asymptomatic, and not folks who got mild symptoms and didn't tell anyone. That's going to be basically every young person. Only the old end up in hospital and they're dramatically worse hit.
Population studies are not directly comparable. A global CFR of 1.5-2.5% sounds right, but that doesn't mean that's a mortality rate. The mortality rate is closer to 0.37% based on the population study I cited.
You seem to be arbitrarily multiplying and dividing CFR by 2 to fit a narrative. I'd love to see other population data but I think this was the first and only study, which is why the numbers are much different than you're citing.
Does the town have any nursing homes? Those are accounting for a large percent of deaths in the United States. (Around 20% in California). If a small town has already shipped its least healthy population away, its IFR will look lower.
Although for what it's worth Iceland is showing 6 deaths and 1600 confirmed cases for a fatality rate of --- wait for it --- 0.35%.
[1] https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e3.htm#T1_down