Here is the best study I have seen so far which ran a real test
I'd make a couple of points on that...
50% confirmed cases had no symptoms.
No symptoms at the time they were tested. That doesn't mean they never developed symptoms later.
The other confirmed 50% show mild cold like symptoms.
Mild symptoms at the time they were tested. That doesn't mean their symptoms didn't worsen later.
I bring that up because it seems to be emerging that there can be a 2-5 day period where the person is infected and infectious yet not feeling symptoms. That may develop into a Flu like illness for 1-2 weeks of varying severity (possibly due the the volume of initial viral load of the exposure), and some percentage can become severe enough to require hospitalization, and some of those become fatalities. I've seen some interviews where doctors had patient they though were responding to treatment and had a good prognosis, die within 24 hours from a sudden worsening.
When you mass-test a population like that, you are simply taking a snapshot and capturing where everyone is at that moment along that progression timeline in a freeze-frame. It doesn't mean their progression stays frozen.
And hence many more people are and were infected, but they simply never knew it.
This study doesn't suggest that in anyway to me. If anything it suggest higher danger because some are running around infectious for a time and not realizing it. And all that taking temps at an airport, may not be catching many infectious vectors.
However, there are serum anti-body tests that are coming soon that if we get wide-spread testing deployed and we see large percentage the population show anti-bodies with them not having known they were ill, then that would be encouraging as it means we would be closer to herd immunity than we realized. But I've seen nothing that leads me to pin my hopes on that yet. I await the data.
[Edit] As you mentioned. I agree.
Only a big sample study testing for the antibodies will give us a real picture of what is and has been going on.
On the other hand, it looks like it will have taken less than 2 days to double the death count from the 26th instead of 3 days. That's a bad thing. You can't project along that trend line forever, but given the 1 month lag time between infection and fatality, I think you could project along it 3-4 week with 85% confidence. And that is based on hard data, not guess numbers of untested infection.
Bloody April will be a real eye-opener for a lot of people. May won't be much better but maybe we will start to see the benefits of the current lock-down.
