Yesterday, the government said there were probably 10,000 coronavirus
cases already, but did not give any indication of how that number was
estimated.
In the absence of widespread testing, the only reliable data we have is
the number of deaths.
I hesitate to send this, but if the government will not supply the
evidence for its strategy then people will do their best with the sparse
data available. Like this:
==
Number of deaths=8 in UK as of 12th March 2020.
Assumption: 8 deaths represents 1% of cases, which implies 8*100/1=800
cases (most of these deaths happened before 12th March, so the final
result below is an under-estimate).
Assumption: Delay D=14 days between infection and death days.
This suggests there were 800 cases 14 days ago.
Source: Real estimates of mortality following COVID-19 infection
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30195-X/fulltext
Assumption: Rate of infection increase R=0.33 per day (probably an
over-estimate).
Sourc: Rate of increase in many countries; hopefully less in the UK, see
https://twitter.com/MarkJHandley, and attached graph for example.
Taken together, this implies there are (1+R)^D = (1+0.33)^14 = 43,352
cases today.
==
I recognise all of this is based on minimal evidence and uncertain
assumptions. But if it is even roughly correct, the extrapolation from
over the next 30 days is worrying.
So, here is my question: Why is the government not testing widely?
Without having access testing data, who knows which part of the sigmoid
infection curve we are on at any given time?
And, FYI I am not an epidemiologist, and I'd really like to be wrong
about almost everything above.
regards,
Jim Stone
--
James V Stone
Honorary Associate Professor,
Sheffield University, UK.
Web: sebtelpress.com
Twitter: @jgvfwstone
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