In September I wrote about the timings of lockdowns. That is this post here. In that post I discussed the various measures of mortality and what they mean. Put simply, the best measure of the overall effect of the pandemic is the excess mortality and the best way of tracking the pandemic in real time is with the daily in-hospital deaths published by NHS England here.
When I wrote in September, I was simply exploring the first wave from the Spring. The assumption that underlies all of this is that the lockdowns work. There is a lot of international data to support this assumption; and it is very reproducible. Basically the peak of deaths occurs around 2 weeks after lockdowns are instituted. Hence the arugment is very simple - if you change the time of the lockdown you change the time when the peak is reached. Because of exponetional growth of the virus, moving this peak has very large effects on the overall death toll.
Here is the figures plotted from 1st March 2020 to 1st March 2021:
This graph shows the daily in-hospital deaths in England for each individual day. The blue line is the daily deaths. The red line is a seven-day rolling average. The reasons for using that figure is that is smooths out the natural daily variation. The shaded areas show the three national lockdowns. The darker shading is the time from initiation of lockdown to the peak (the ligher shade being the rest of the lockdown).
It is important to note that by using death figures the peak is behind the peak of infections. (I discussed perviously why this is the best measure but it is important to realise this time delay is implicit in the data).
One thing that is very noteworthy here is the timing from lockdown to peak of deaths. The first lockdown was 23rd March; the peak of deaths was 8th April (16 days later). The second lockdown was on 5th November; the peak was 25th November (20 days). Third lockdown, 5th January; peak 19th January - 15 days.
There is a lot of work to do studying these; it is known (although the data is imcomplete) that survival rates have improved in the second wave as we have better treatment protocols from lessons learnt from the first wave. It is also true that the accelaration phase of the waves was slower in the second and third waves than in the first. In the first, the number of deaths per day increased from 159 on the day of lockdown to 900 at the peak in 16 days; that an increase in the death rate of 46/day. In the second lockdown the rise was 5.4/day and in the third 16/day. These differences may be simply a feature of the phase of the exponetial rise when the lockdowns were instituted or may reflect that prior to the 2nd and 3rd lockdowns, various restrictions were still in place. Or there may be a different explanation such as better medical care.
Anyway, the whole point of my previous post was that earlier lockdowns have big effects. One of the implications of this chart is simply that the relaxation of the lockdown from 5th November after only 4 weeks was far too early. But I also want to ask the question, what would have happened if the Autumn lock-down had been two weeks earlier?
Here's what that looks like:
As I discussed before, the only assumtion I am making here is that the lockdown would cause cases to fall at the same time interval; i.e. if lockdown occurred two weeks earlier, the peak would be two weeks earlier.
The pink shading is the actual 4 week lockdown that we had. The green shaded area is a lockdown started on 22nd October and running until the death rate was the same as when the spring lockdown was relaxed.
The dotted lines show the expected death rates going forward, if the pandemic follows the same sort of trajectory as it has done previously. I will post in the future, a comparison between these predicted figures as the real ones.
So if a lockdown had been instituted on 22nd October 2020 and it had been as effective as expected what effect would that have of the death rates?
Well: Currently the number of in-hospital deaths in England is around 69,000 (upto 24th January 2021). If the lockdown had been instituted on 22nd October and worked as this graph suggests then that total would be 41,000. That's 40% fewer deaths.
The official UK deathtoll from Covid-19 is currently 106,000. As I discussed before, the excess death figure is the best one to use but if we simply take that figure at reduce it by 40% then we are talking about OVER 42,0000 fewer deaths if we had acted sooner in the Autumn.
In my next post I will discuss a bit more the issues around politics and decision-making and how I think this mistake in the Autumn a gross error of government with the cost being massively high.
AFZ
