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CMI notes further excess deaths but inflated by holiday closures of Register Offices

During the coronavirus pandemic, the Continuous Mortality Investigation (CMI) is publishing frequent UK mortality analysis through its mortality monitor. The latest update covers week 52 of 2020 (19 to 25 December) based on provisional England & Wales deaths data published by the Office for National Statistics (ONS) on 6 January 2021.

The key points of this update are:     

  • The number of deaths with COVID-19 mentioned on the death certificate was 2,912 in week 52, compared to 2,986 in week 51. However, the week 52 figure is relatively low due to Register Offices being closed on the Christmas Bank holiday, which fell at the end of week 52.
  • There were 51% more deaths registered in England & Wales in week 52 than if death rates had been the same as for week 52 of 2019. The corresponding figure for week 51 was 7%. We caution that the figure for week 52 is inflated, due to there being one bank holiday in week 52 of 2020, but two bank holidays in week 52 of 2019.
  • ONS will report 53 weeks of registered deaths data this year, compared to 52 weeks in most years. Next week’s figures, for week 53 of 2020, will cover the remainder of the year’s registered deaths and will also be affected by bank holidays.
  • There have been around 75,000 more deaths in the UK from the start of the pandemic to 25 December 2020 than if mortality rates were similar to those experienced in 2019. Of these, 14,200 have occurred in the second wave.

Cobus Daneel, Chair of the CMI Mortality Projections Committee said:

“Excess deaths are inflated for week 52 of 2020, because it only had one bank holiday, while week 52 of 2019 had two. All indications are that we would have seen excess deaths in week 52 even with a consistent pattern of bank holidays.”

All mortality monitor weekly updates are publicly available on the mortality monitor page.

“Excess” deaths are the difference between actual deaths in 2020, and those that we would expect if mortality rates had been the same as in 2019.

The ONS data released today relates to registered deaths. As Christmas Day fell at the end of week 52 of 2020, there were fewer deaths registered in that week than would otherwise have been the case. As week 52 of 2019 had two bank holidays, Christmas Day and Boxing Day, its registered deaths were even lower, so the excess deaths for week 52 (comparing 2020 to 2019) are inflated.

The publication of ONS data broadly follows ISO week numbers. Most years have 52 ISO weeks, but because a 52 week year has 364 days, less than a calendar year, some years have “leap weeks” under the ISO system.For the purposes of the mortality monitor, the CMI treats the first wave of the pandemic as being week 10 onwards (i.e. from 29 February 2020) and the second wave as being week 38 onwards (i.e. from 12 September 2020).

The CMI intends to publish its next mortality monitor for week 53 on Tuesday 12 January 2021, alongside its end-2020 quarterly monitor.