Another unknown figure which will vary from country to country.
We have been promised some initial results from the ONS serological survey next week. This may narrow it down further?
Working backwards, if we take say 35,000 UK deaths at a rate of 1% then we would expect around 3.5 million to have been infected so far?
If we adopt the flu figure of 0.1% fatality then that would equate to 35 million people having been infected.
There has been mention of a figure of around 10% of the population been infected which would mean around 6.7 million. This will of course vary regionally per head of population but I understand that variation is part of the study.
That in turn would extrapolate to a fatality rate of between 0.5 to 0.6%
The true fatality rate will only be known a very long way down the line, but if it turns out only 10% have been infected we would be a very long way from any herd immunity, even assuming we do actually develop some natural immunity?
One to watch?
So many questions are still unanswered, still so much we don't know about Covid-19 and how far it's spread. As we keep being told, and it's undoubtedly true, we won't really know what the hell went on until it's all over

.
The natural immunity thing is very scary, if we can't develop a real and/or lasting immunity from having suffered from it previously, we're pretty deep in the shit. I'm assuming if that's the case, similarly it will be even harder to develop a universal vaccine? That really would be a nightmare scenario.
Personally, I'm just hanging on to the possibility of the much-fabled Oxford vaccine becoming a real prospect by September, and then rolled out asap to the whole UK population, perhaps before the year is out? I realise that's very optimistic.
One thing I found very interesting regarding that: when they announced a couple of weeks ago that they'd given the vaccine to some volunteers, obviously there's a control group given a placebo as well as those given the vaccine, the groups are of equal size and the same average age range presumably. The obvious question on my lips as a layman, was will you then expose both groups to Covid-19 to get a fast result as to whether it works or not? But of course no, this would be unethical and it goes against the Hippocratic Oath I guess...instead, those people are simply allowed to go back into the population and pick it up or otherwise, by natural means of 'accidental exposure'.
While that's ethical (and of course, actually more meaningful from an epidemiological POV) I did wonder whether there might be some
hardcore volunteers at Porton Down that we didn't know about, who might simply be exposed to Covid-19, having been given the vaccine?