Vaccine coverage and denominators

What proportion of people had the Covid-19 vaccine?

What share of people have had a Covid-19 vaccine dose? For the United Kingdom on 25th May, different sources give different statistics:

• Public Health England: 72.9% (of the adult population)
• Our World in Data: 56.5% (of the total population)

There is a conceptual difference. PHE uses an Office for National Statistics estimate of the UK population aged 18 or over (~52.6m). Our World in Data uses the UN World Population Prospects 2019 estimate for 2020 (~67.9m).

Both are valid statistics. It is important to see the vaccine coverage of those eligible, and of the total population. Vaccine eligibility may change.

What about vaccine coverage by age groups?

This is more complicated.

The latest NHS England vaccination report has vaccinations up to 23rd May. It states over 100% of 75–79 year-old people received at least one dose.

Vaccine coverage by age using the 2019 population estimates is likely to be too high. The question is: why?

People age. As people get older, they move into more senior five-year age groups. Some of the people who were 73 or 74 in June 2019 are now in the 75–79 age group.