UK percentage of population infected.
Anyone (W?) want to justify W's guess of 50% people have prior infection?
I have two ways to approach this:
(1) measurement of N IgG antibodies, these are not generated from the vaccine and can be seen after natural infection. They are easily measured: 18% of population.
Caveat: they to decrease with time and after 12 months maybe 50% or more have low levels
(2) Count cases, correct for infections.
We know from ONS survey that the ratio of infections (even asymptomatic) to cases is now reliably around 1.6. We count cases accurately: 8M at the moment, for a population of 69M.
Caveat: there have been times (1st wave) when testing was limited and cases dramatically underestimated infections.
I got some reassurance from both methods coming to the same answer:
8/69 * 1.6 = 18%
Current N IgG (sampled) 18%
I then added 50% (arbitrarily) to allow for undercounting errors and get 25%. Some would argue that is too much. The official figures go with the N antibody count at 18%. And of course if counting N antibody mediated immunity that is correct.
W seems to have another factor of 2 in there somehow.
These boring numbers matter - because they do alter the best fit interpretation of what is going on - e.g. how much protection are the vaccines giving against transmission - that of course informs public policy.
And everyone should remember, the figures quoted are averages.
Everything about coronavirus varies with age. Including vaccine efficacy since vaccines are using the bodies natural defences - which wane with age. So young people, vaccinated, will have much better protection against transmission than age 60+.
Really, the best correction for thinking people against antivaxxer propaganda is to look very closely at the numbers. To make antivax memes stick you need to skew them all. That was easier in the earlier days of the pandemic than it is now. However in the real world antivaxxer propaganda is a smart video in a social media feed and has no relationship to numeric reality at all.