FOI Ref: FOI/2022/4708
You asked
Throughout the last two years a number of your publications have mentioned rates of death per 100,000 people. In order to work out rates you must have a total number in the first place, so I would like to know what number was used to work out the total number of people who are unvaccinated for Coronavirus (COVID-19)?
To give the rate of death in the unvaccinated you must know this number. Can you please explain where you get this number from? Is it exact? It is based on estimations? Does it change month on month? And most importantly can you share the exact calculation you used (and therefore the exact number of people unvaccinated for covid) to work out your most recent rates of death for the unvaccinated?
We said
Thank you for your request.
Our accompanying dataset to the Deaths involving COVID-19 by vaccination status, England publication includes monthly Age Standardised Mortality Rates (ASMRs) by vaccination status for deaths involving COVID-19, non-COVID-19 deaths, and all deaths. These are broken down by age group and sex for the population in the Public Health Data Asset (PHDA) using data on death occurrences The dataset also includes counts of deaths by vaccination status and weeks since vaccination for all registered deaths. The number of deaths can be found in column E on table 1 of the dataset.
This publication uses death occurrences registered up to 8 June 2022, rather than death registrations. Because of registration delays, more deaths may be registered at later dates, leading to an increase in the death occurrences.
To compare mortality across Coronavirus (COVID-19) vaccination statuses, ASMRs are calculated. ASMRs are used to allow comparisons between populations that may contain different proportions of people of different ages. The 2013 European Standard Population is used to standardise rates. Methodological information on the calculation of ASMRs can be found in our Weekly COVID-19 age-standardised mortality rates by vaccination status, England: methodology article.
In our publication Deaths by Vaccination Status, we publish age standardised mortality rates for different vaccination statuses. The rates are based on the population who are enumerated in the 2011 Census and registered with a GP in 2019, which enables us to link on vaccination and mortality datasets and obtain reliable estimates of the population by vaccination status, which is especially important for the unvaccinated population for whom it is difficult to get an accurate estimate. The sample covers approximately 79% of the population of England aged 10+. The age standardised mortality rates take into account differences in age between different vaccination status groups but not other factors such as health. These other factors can affect the rates, particularly for example when people who are more clinically vulnerable have been prioritised for vaccination. In addition, where the populations in vaccination status groups are small as people move through the vaccination status groups, the rates can have wide confidence intervals and be more volatile. The rates should therefore be interpreted in the context of who is more likely to be vaccinated at the time and the size of the population and confidence intervals.
A glossary of terms used in this article, other strengths and limitations, and further information can be found in our previous Deaths involving COVID-19 by vaccination status bulletins from May 2022 and December 2021.