Covid-19: England’s daily deaths are still “likely to exceed” first wave peak despite projection changes
BMJ 2020; 371 doi: https://doi.org/10.1136/bmj.m4321 (Published 06 November 2020) Cite this as: BMJ 2020;371:m4321Read our latest coverage of the coronavirus outbreak
The UK government has admitted to errors in slides showing forecasts of daily covid-19 hospital admissions and deaths that were used to support a second lockdown in England,1 leading to concerns over transparency and whether the restrictions were justified.
In slides presented during a 31 October televised address, the medium term projection suggested that daily deaths in England could reach 800 by 8 December. However, the area of uncertainty around this figure showed that deaths could exceed the first wave peak of 1000 by late November and rise to nearly 1500 by 8 December.
This area of uncertainty has now been changed to show that, at the upper end of the projection, daily deaths would just exceed 1000 deaths by 8 December. Similarly, the area of uncertainty around the daily hospital admission projection has been updated, reducing the maximum from nearly 9000 to 6000 by 8 December. Again, the central projection remained the same—exceeding the first wave peak of 3000 by 24 November and reaching around 4500 by 8 December.
In the updated slides2 the government says that the graphs have been “amended after an error was found in the interquartile ranges for SPI-M [Scientific Pandemic Influenza Group on Modelling] medium term projections. This does not affect the insights that can be taken from these analyses.”
Public confidence
Concerns have been raised over the errors, especially since the projections were used to justify a second lockdown. However, David Spiegelhalter, a statistician who chairs the Winton Centre for Risk and Evidence Communication at the University of Cambridge, told The BMJ, “The central projection is unchanged and lies below the first wave peak on 8 December, but the uncertainty interval has altered so that the probability of a breach on 8 December is reduced.
“Apart from the emotional impact of the image, the information is not materially different: according to these projections the death rate is still extremely likely to exceed the first wave peak in December.”
While the amendments may not have changed the resulting action, many experts are calling for the government to be more transparent with data.
The Office for Statistics Regulation has issued a statement3 urging the government to review the way it communicates covid-19 data to the public. It said that the data had not been consistently supported by “transparent information,” resulting in confusion and potentially undermining public confidence. The situation could be improved by publishing sources of data, the methodologies and key assumptions of models, and the underlying data of statistics, it said.
David Norgrove, chair of the UK Statistics Authority, said, “I recognise the pressures faced by all those working on decisions related to coronavirus. But full transparency of data used to inform decisions is vital to public understanding and public confidence.”
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