Weekly all-cause mortality surveillance (week 26 report, up to week 22 2023 data)
Updated 7 September 2023
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In week 22 of 2023, statistically significant excess all-cause mortality was not observed:
- by week of death overall in England through the EuroMOMO algorithm
- in Northern Ireland, Scotland or Wales
Excess all-cause (EuroMOMO) mortality in subpopulations, UK
In England, statistically significant excess mortality by week of death above the 2 z-score threshold was not seen overall in week 22 of 2023, nor in any age group or region. This was after correcting General Register Office (GRO) disaggregate data for reporting delay with the standardised EuroMOMO algorithm (Figure 1).
In the devolved administrations, no statistically significant excess all-cause mortality for all ages was observed in Northern Ireland, Scotland or Wales in week 22.
This data is provisional because of the time delay in registration, so numbers may vary from week to week.
Data presented in this week’s report supersedes data presented in reports from previous weeks.
Figure 1: Weekly observed and expected number of all-cause deaths in all ages, with the dominant circulating respiratory virus, England, 2017 to week 22 2023
Note: the recent weeks’ data are estimates which may be subject to registration delay corrections and therefore should be interpreted with caution. These estimates may differ substantially from future reports as more deaths are registered.
Table 1: Excess mortality by age group, England*
| Age group (years) | Excess detected in week 22 2023? | Weeks with excess since week 40 2022 |
|---|---|---|
| <5 | No | 45 to 46, 6 |
| 5 to 14 | No | 49, 51, 11 |
| 15 to 64 | No | 41 to 42, 44, 47 to 2 |
| 65+ | No | 40 to 42, 49 to 3 |
Table 2: Excess mortality by UK country, for all ages*
| Country | Excess detected in week 22 2023? | Weeks with excess since week 40 2022 |
|---|---|---|
| England | No | 40 to 42, 47, 49 to 3 |
| Wales | No | 50 to 1 |
| Northern Ireland | No | 42 to 44, 48, 50 to 2 |
| Scotland | No | 40, 42, 45, 49 to 3, 10 |
*Excess mortality is calculated as the observed minus the expected number of deaths in weeks above threshold.
Note: separate total and age-specific models are run for England, which may lead to discrepancies between Table 1 and Table 2.
All-cause death registrations (ONS), England and Wales
The provisional number of weekly deaths registered in England and Wales is published online by the Office for National Statistics (ONS).
Data interpretation and further information
Seasonal mortality is seen each year in England and Wales, with a higher number of deaths in winter months compared to the summer. Additionally, peaks of mortality above this expected higher level typically occur in winter, most commonly the result of factors such as cold snaps and increased circulation of respiratory viruses, in particular influenza and in summer occasionally because of heatwaves.
This weekly mortality surveillance aims to detect and report acute significant weekly excess mortality above normal seasonal levels in a timely fashion. Excess mortality is defined as a significant (above the upper 2 z-score threshold) number of deaths reported over that expected for a given point in the year, allowing for weekly variation in the number of deaths. A z-score is a statistical measure of how many standard deviations above the baseline threshold the number of deaths were. For example, a z-score of 2 means that the number of deaths were 2 standard deviations above the baseline threshold.
The COVID-19 pandemic period is excluded from the baseline thresholds calculation. Excess mortality triggers further investigation of spikes and informs any public health responses.
The aim is not to assess general mortality trends or precisely estimate the excess attributable to different factors, although some end-of-winter estimates and more in-depth analyses (by age, geography, and so on) are undertaken.
Separate to the calculations presented in this report, excess winter deaths (EWD), comparing the number of deaths in the winter period with the non-winter period, are calculated by the ONS.
Other measures of excess mortality published by the UK Health Security Agency (UKHSA) or the Office for Health Improvement and Disparities (OHID) are the Fingertip excess mortality in England report, which uses ONS death registration data, and the UKHSA daily GRO mortality model, which is published in the weekly influenza and COVID-19 surveillance report.
Glossary
Z-score
A z-score is a statistical measure of how many standard deviations above the baseline threshold the number of deaths was. For example, a z-score of 2 means that the number of deaths was 2 standard deviations above the baseline threshold.