As this outbreak is now over 2 months old, I'm trying to use a bit of hindsight, along with a sceptical appraisal of where this bloody virus is actually headed, because I have a suspicion using the day-by-day numbers are giving an incorrect impression. The spread of cases unconnected to previous case or China is the clue, for me.
13 January:
Thailand reports first case of covid-19.
On 29 February they have 42 cases.
22 January:
USA finds first case.
On 29 February, USA has 68 cases identified, most of which are ex-China.
22 January:
Above, a photograph shows queues at Wuchang train station in Wuhan, China. [Ahead of the lockdown]
22 January:
First case hits the Philippines
On 29 February, Philippines have had zero more cases.
23 January:
Researchers from the MRC Centre for Global Infectious Disease Analysis at Imperial College London now estimate that there have probably been about 4,000 cases in Wuhan. [Official number was 400 at the time]
25 January:
Four cases identified in Australia.
On 29 February, Australia has 25 cases.
31 January:
When does this go exponential?
I saw 6,000 then up to 7,000 and now 10,000? If this was going exponential then we should now be in the millions.
I mention this because there was talk of exponential spread upthread.
Pandemics are discovered when the serious cases show up. Prior to that, nobody's looking, so the infection can spread by mild cases long before those serious cases are seen, and we know for certain covid-19 not only produces mild cases, but also completely asymptomatic ones.
Imperial College London has always maintained actual numbers are at least ten times the officially identified cases. I suggested at the start that it could be as high as 100 times more, and the way cases with no contacts in China are now springing up gives a strong likelihood of under-reporting.
This was noted all the way back on 17 January, when people started applying maths to the situation.
Based on a r0 of 2.6, we would be seeing something in the order of 1,000,000 cases right now.
And maybe we have that, but haven't counted 90% of them because those people aren't sick enough to bother going to the doctor.
I'm going to say that's where we actually are, and it's going to be impossible to control or even limit the spread now it has clear traction.
I think we're over-estimating the deadliness by under-estimating the spread and there seems to be no other way the virus could be spreading internally in cases with no connection to past cases, other than wrong input.
It's still going to be a nightmare for health systems, but I think attempts to slow the spread are futile and we're stuck with this as an extra human pathogen until someone strikes a vaccine. (which may not work if the virus mutates)