Excess deaths can be defined as the difference between the actual number of deaths in a particular period and the estimated number of deaths expected in that period. Expected deaths can be derived in a variety of ways for different purposes, which means that there may be different estimates of excess deaths published by different organisations and used for those specific purposes. Excess deaths attributable to specific factors – such as hot or cold temperature – can also be estimated by using a statistical model of the relationship between the factor and the number of deaths.

This document explains the major publications related to excess deaths in the UK. Details of the methodologies are published by individual organisations.

ONSHow reportsdeaths are counted

Deaths

The majority of deaths are not registered weeklyon inthe Englandday andthey Wales

The Deathsoccurred registered(more weeklydetails are available here). Some of the publications listed in Englandthis andexplainer Wales publicationcount includesthe estimatesnumber of excessdeaths all-causeby mortalitythe indate Englandthe death was registered, and Wales.

Onsome 20count Februarythe 2024, ONS publishednumber aof newdeaths methodby forthe measuringactual excessdate mortalitywhen the death occurred . Publications which use the date of registration avoid uncertainty about deaths that willhave allowoccurred nationaland comparisonsnot been registered yet, but are less precise about the timing of excessdeaths deaths.(for Ininstance a death which occurred on a Saturday would not be registered until the future,following Monday at the weeklyearliest, publicationand willusually includelater). numbersPublications which use the date of death registrationsoccurrence allow more precise attribution of potential causes of changes in mortality rates over time, but usually have only partially complete data due to the delays in registration of deaths.   

The main publications and how they can be used

Deaths registered weekly in England and Wales, the Office for National Statistics

This publication contains the headline figures on death registrations and excess deaths for England and willis be the most appropriate for making comparisons across each of the devolved administrations of the UK.

NRS and NISRA currently produceThe excesspublication mortalityalso figuresincludes for Scotland and Northernnumbers Ireland,of respectively,death registrations and haveexcess updateddeaths theirfor methodologyeach inof linethe with4 thatUK implementedcountries by ONS.as Thiswell meansas athe consistentUK methodas isa usedwhole. byThe allstatistics 4are nations,broken whichdown enablesby comparisonsage atand national level.sex.

On 20 February 2024, ONS’s published a new methodologymethod for estimatingmeasuring theexcess expectedmortality.

ONS’s numbermethodology of deaths, which replaces the previous 5-year average approach, is closely aligned with OHID’s updated methodology described below. Both organisations publish estimates of excess deaths for England. Those produced by ONS are consistent with estimates for other UK countries,countries. whileHowever, those produced by OHID can’s methodology can be disaggregated by local authorities within EnglandEngland, (atwhereas present, ONS’s new methodology permits only regional breakdowns in England).England.

OHID reports

Excess mortality withinin England:England, post-pandemicOffice methodfor Health Improvement and Disparities

This onpublication mortality,is the newmost approachappropriate providesto ause methodwhen forcomparing ongoingexcess monitoringmortality whichwithin includesEngland. The anpublication updatedprovides baselineestimated period.numbers These estimates represent the number of excess deaths aboveand the numberratio expected, based on trends in mortality over the previous 5 years instead of comparingregistered to theexpected pre-pandemicdeaths. period.Users Furthercan detailsadjust are captured in ’Changes to OHID’s reporting of excess mortality in England’ (published alongside the report).

Thistime publicationperiods ispresented, theallowing mostcumulative appropriateestimates to usebe whenshown comparingfor excessspecific mortalityperiods. within England. OHID produces breakdowns which show inequalities in levels of excess mortality, including by sex, age group and level of deprivation for the English regions and local authorities. OHID’s analysis by cause of death describes which causes are particularly contributing to excess deaths in specific time periods.

OHID’s first monthlypublished publicationthis providesrevised estimatedversion numbers of excessits deathsreport on 20 February 2024. This new analysis and methodology is aligned with ONS’s method where possible. These estimates represent the rationumber of registereddeaths toabove expectedthe deaths.number Usersexpected, canbased adjuston trends in mortality over the timeprevious periods5 presented,years.

Weekly allowingall-cause cumulativemortality estimatessurveillance toreports, beUK shownHealth Security Agency

All-cause mortality surveillance shows time periods when mortality levels were higher than expected, rather than providing an estimate of the number of actual or expected deaths. The weekly all-cause mortality surveillance reports are published every Thursday.

This publication includes details of the weeks in which observed deaths arewere higher than an expected threshold, which is calculated using a European-wide algorithm called Euromomo. It includes a chart of observed and expected deaths by the date the death occurred across all ages in England. The chart also shows the upper limit for when the number of deaths is considered to be significantly higher than expected.

This publication can be used for making international comparisons and for other surveillance purposes, prompting further investigation to determining the cause, and assessing the impact of known health events. Health events could include high levels of influenza, extreme heat or extreme cold, for example.

AnnualSurveillance heatof mortalityinfluenza monitoringand inother Englandseasonal respiratory viruses, UK Health Security Agency

The surveillance of influenza and other seasonal respiratory viruses in the summerUK statistics months,are UKHSApublished every year after the winter period.

This publication includes estimates of the number of deaths causedattributable byto influenza, COVID-19 and extreme cold using all-cause mortality data.

This publication can be used to indicate the potential mortality burden from COVID-19, other respiratory diseases and extreme cold.

The report uses an adapted version of the FluMOMO model, which was developed to incorporate COVID-19, details of which are given in the 2023 working paper.

Annual heat usingmortality monitoring report, UK Health Security Agency

UKHSA estimates the number of deaths associated with heat in each summer. Heat episodes are defined as anyperiods dayin on which an amber Heat-Health Alert (HHA) is issued in at least one region, or the mean central England temperature is at least 20°C. OneDeaths dayduring eitherheat sideepisodes ofare thecompared alertwith ordeaths meanin temperaturea isbaseline alsoperiod included(the to14 allowdays forbefore theand time-lagged14 effectsdays ofafter temperaturea onheat episode) to estimate heat-associated mortality. WhereYears episodesof overlap,life theylost are countedalso calculated, as onea episode.measure of premature mortality. The data on deaths is stratified by NHSheat Englandepisode, region,region and age group,group. Since 2023, a breakdown by sex andhas heatbeen period.included. FiguresIn are2024, reportedfurther forbreakdowns heat-associatedby deathslocal resilience forum area, place of death and yearscause of lifedeath lost.were added.

TheAdditionally, in the 2022 report onwards the publication includesprovides a plottedcomparison graphbetween forobserved thosedeaths agedand 65modelled yearsestimates. andThe overmodelled ofestimates dailyare all-causederived excessby mortalityapplying anda heat-attributablestatistical mortalitymodel inof England.the Antemperature-mortality additionalrelationship plotin comparesEngland in the totalprevious all-cause5 excessyears mortalityto estimatesthe usingtemperatures observed deathsin andthat modelledsummer. excessThis all-causeallows mortalityidentification byof heat episodeepisodes andwhere totalheat-associated estimatedeaths acrosswere allhigher episodesor inlower England.than would be expected for those temperatures.

UKHSA’s heat mortality monitoring provides information on heat-associatedexcess deaths observed during episodes of heat each year (known as heat-associated deaths) to inform public health actions.actions Itand alsothe providescontinuous informationimprovement toof the publicWeather-Health Alerting system in England. It provides information on the observed impacts fromof heat on health.health, and how these impacts vary depending on temperature and other factors. The publication alsocan servesbe asused ato basisunderstand totrends updatein the Weather-Healthnumber Alertsof (WHA)heat temperatureepisode thresholds.

Annualdays surveillanceand heat-associated deaths over time. It forms part of influenzamonitoring progress against the goals of the Adverse Weather and otherHealth seasonalPlan respiratoryfor virusesEngland to reduce mortality and premature mortality related to adverse weather.

Climate-related mortality in theEngland UKand Wales, Office for National Statistics

The publication compares the winterrelative period.risk of death associated with a range of temperatures, including both cold and heat, with breakdowns for English regions and demographic characteristics.

ThisThe publicationONS includeshas estimatesworked in collaboration with partners at the London School of Hygiene and Tropical Medicine, the numberDepartment of deathsHealth attributableand toSocial influenza,Care COVID-19(DHSC) and extremeWellcome coldto usingdevelop all-causethis mortalitymethod, data.that adopts techniques used widely in climate research globally. These are Official Statistics in Development. The methods are under development, which means estimates may change.

ThisThe ONS publication canincludes beattributable useddeaths associated with heat and cold. These estimates represent a modelled estimate of excess deaths associated with hotter and colder days, based on temperatures experienced across different locations, while adjusting for other factors influencing mortality. This method uses daily deaths and daily temperatures occurring over 35 years to indicatemodel the potentialassociation mortalitybetween burdenoutdoor fromtemperature COVID-19,(both heat and cold) and mortality. It adjusts for seasonal and long-term trends, as well as other respiratoryfactors diseasesinfluencing mortality trends, such as air pollution, and extremewas cold.developed based on global scientific research which focuses on the impacts of climate change. This approach provides insight into the impact of a range of temperatures, incorporating delayed effects because studies have shown that temperature-related deaths can occur some time after the exposure to hot or cold weather.