Data on excess mortality during the COVID-19 pandemic by Our World in Data

For more general information on our COVID-19 data, see our main README file in /public/data .

Data sources

The reported all-cause mortality data is from the Human Mortality Database (HMD) Short-term Mortality Fluctuations project and the World Mortality Dataset (WMD). Both sources are updated weekly. We also present estimates of excess deaths globally that are published by The Economist.

WMD sources some of its data from HMD, but we use the data from HMD directly. We do not use the data from some countries in WMD because they fail to meet the following data quality criteria: 1) at least three years of historical data; and 2) data published either weekly or monthly. The full list of excluded countries and reasons for exclusion can be found in this spreadsheet.

See here for a full list of source information (i.e., HMD or WMD) country by country.

We source our baseline of projected deaths for 2020–2023 from WMD.

We calculate the number of weekly deaths for the United Kingdom by summing the weekly deaths from England & Wales, Scotland, and Northern Ireland.

For a more detailed description of the HMD data, including week date definitions, the coverage (of individuals, locations, and time), whether dates are for death occurrence or registration, the original national source information, and important caveats, see the HMD metadata file.

For a more detailed description of the WMD data, including original source information, see their GitHub page.

For a more detailed description of The Economist's estimates, including metadata, source information, details of their methodology, and their presentation of the estimates, see their GitHub page.

Excess mortality data from HMD and WMD that is collated by Our World in Data

Stored in excess_mortality.csv .

As of 28 March 2023, the data columns are:

How P-scores are defined and calculated

As of 20 September 2021, we calculate P-scores using the reported deaths data from HMD and WMD and the projected deaths from WMD, as an estimate of expected deaths. The P-score is the percentage difference between the reported number of weekly or monthly deaths in 2020–2023 and the projected number of deaths for the same period based on previous years.

As of 18 January 2022, we use the separate projected deaths baselines for 2020, 2021, 2022 and 2023 published by WMD. Previously we used—and WMD only published—a projection for 2020.

Before 20 September 2021, we calculated P-scores using a different estimate of expected deaths: the five-year average from 2015–2019. We made this change because using the five-year average has an important limitation — it does not account for year-to-year trends in mortality and thus can misestimate excess mortality. The WMD projection we now use, on the other hand, does not suffer from this limitation because it accounts for these year-to-year trends.

Important points about the data

For more details see our page on Excess mortality during the Coronavirus pandemic (COVID-19).

The reported number of deaths might not count all deaths that occurred. This is the case for two reasons:

The date associated with a death might refer to when the death occurred or to when it was registered. This varies by country. Death counts by date of registration can vary significantly irrespectively of any actual variation in deaths, such as from registration delays or the closure of registration offices on weekends and holidays. It can also happen that deaths are registered, but the date of death is unknown — those deaths are not included in the weekly or monthly data here.

The dates of any particular reporting week might differ slightly between countries. This is because countries that report weekly data define the start and end days of the week differently. Most follow international standard ISO 8601, which defines the week as from Monday to Sunday, but not all countries follow this standard. We use the ISO 8601 week end dates from 2020-2023.

Deaths reported weekly might not be directly comparable to deaths reported monthly. For instance, because excess mortality calculated from monthly data tends to be lower than the excess calculated from weekly data.