Corona Days


07-Jun-2020
Shopping at the local supermarket I saw only three other shoppers with face masks. I know availability is a problem in the UK, but it is easy to make a DIY version.

An additional precaution I am taking is a daily vitamin D supplement (12.5 micrograms). There appears to be a match between groups most likely to have a deficiency and those more badly affected by the virus, which could be just a coincidence, but provided we stick to the recommended daily dose (400800 IU, or 1020 micrograms) it is unlikely to do any harm.
Healthline: "In the US, about 42% of people may be deficient in this vitamin. This number rises to 74% in older adults and 82% in people with dark skin since their skin produces less vitamin D in response to sunlight."
Other matching characteristics include being male or overweight.
There are a few studies pointing to some connection, e.g. here, and here.

So why is the English virus response so appalling, we have one of the highest deaths per capita in the world. That initial delay in the lockdown was undoubtedly critical at a time when cases were doubling every 3 days, even 1 week delay then leads to a 5 times higher number of cases. (This is an approximation assuming an instant reduction, e.g. from reproduction rate R0=4 to Rt=0.8 which is not exact because there were various voluntary actions giving a small reduction prior to official lockdown, and also, R is just an average throughout the population, and can vary in different groups). There are several differing versions of why the delay happened, the official version believe it or not is that they were 'following the science' and did the right things at the right time.
For comparison the Czech Republic introduced their lockdown before a single death and have only reached 262, while others have done even better. Timing matters.

There are still arguments about how much the timing matters, which is rather odd, maybe the big problem is that we don't have the one statistic we really need to clarify this issue, which is the actual number of infections. What we have instead is the 'number of confirmed cases' which tells us very little beyond the timing and level of testing. In the simplest model with an idealised lockdown the peak in new infections per day will occur immediately before the lockdown date, and then start to fall. Some estimates are of well over a million total UK infections up to the 23 March lockdown, although 'confirmed cases' were just starting to rise then, and peaked 2 or 3 weeks later, probably because it can take a week to develop symptoms, then another week or more to need hospital treatment and/or testing. That missing figure for actual infections may explain the widespread failure prior to lockdown to comprehend the urgency of the situation. That million infected could have become 5 million after another week had no action been taken. That sort of thing is what we might hope 'the scientists' would have understood and advised on. Even without that advice there was enough evidence from other countries to show what was needed, we were 2 weeks behind Italy and could see the future.

'All models are wrong, but some are useful'. Doing a few more calculations I find my 'simplest model' can actually give quite accurate predictions. Assuming fatality rate 1% the initial million infections determine 10,000 deaths to follow. If R was reduced to 0.5 at lockdown the final total would be 20,000, but the actual R=0.7 to 0.8 predicts around 40,000 to date, which is about where we are. What this suggests is that although the timing is by far the most important decision the depth of the lockdown is also vital, getting R down to 0.5 could have halved the fatalities compared to the actual level. The best approach was to lock down early and lock down hard. Neither happened in the UK. There was no trade-off involved, locking down early and hard would have reduced the length of lockdown needed and done less harm to the economy.

I just saw results from antibody tests suggesting over 6% of the UK population have been infected, which is close to 4 million, which matches the 1% fatality figure I assumed, and confirms a plausible figure of a million infections before lockdown.

There are many varying presentations of data, one I find interesting is euromomo. Scrolling down to the 'Z-scores by country' this in effect is an indication of total excess deaths compared to normal, and using the slider at the top we can select just 2020. Previously it appeared that the English graph was stuck on a plateau, which I guessed was some sort of late reporting effect, and thankfully later updates replace this with a downward trajectory, almost back to normality.

Looking around the murky depths of the internet I was a little surprised to see the UK ex-advisor Ferguson being accused of some sort of fraudulent modelling to justify the lockdown. However, returning to daylight, at BlueSkiesResearch, the real story appears to be that his initial modelling greatly underestimated the scale of the problem, having assumed cases to be doubling every 5 days based on early days in Wuhan, when the data here and in other badly affected European countries showed a 3 day doubling. The initial prediction of a peak around mid-summer was way out, we were possibly headed for a peak over 3 million new cases per day within 4 weeks unless drastic action was taken to prevent this. Eventually this was realised, but may be part of the reason for the original delay. I think too much emphasis has been placed on models when just the data alone was sufficient reason for serious alarm. What the data didn't yet tell us was how long the 3 day doubling would continue. One view was that without action it would only start to fall as 'herd immunity' was approached.

Another vitamin D study found that for 780 Covid-19 patients close to 99% of those with vit-D deficiency died. Curiously the study is criticised by Full Fact, not because the 99% figure is incorrect, but because 'there are problems with the study methods'. This seems a common theme with vit-D claims, but these are desperate times, we really don't need to wait for conclusive proof, the vitamin is cheap, easily available, and has other known health benefits.

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