I'm a bit surprised by how small the red bits are in the last charts, in the England one. I thought the UK was about 70% vaccinated. Do those graphs indicate that nearly all of the 30% or so unvaccinated have already had the infection?
% of UK vaccinated depends on how many doses and whether all ages are included or only people over a certain age.
For example at the moment the UK dashboard vaccine stats now use population figures for everyone 12 and older. It used to be higher ages only but they changed it as they opened up vaccination to some younger ages.
Right now for population aged 12 and up the dashboard has UK figures of 90.2% for first dose, 82.7% for second dose, 60.6% for boosters. These figures will obviously drop if we included all younger children in the population figures, and those sorts of total population percentages are what some people prefer to use on twitter etc.
The other thing to keep in mind is that the chart in the tweet will not be 100% accurate, its almost certainly based on the data we get from blood donors, and they arent completely representative of the whole population. When they analyse those samples they have 2 different antibody tests, one that shows antibodies caused by vaccination and infection (Roche S), and one that only shows antibodies caused by infection (Roche N).
See pages 41 to 47 of this report for loads of details, charts etc:
Here is some of the text from that which is relevant. The blood donors are aged 17 and over.
Roche S seropositivity in blood donors has plateaued and is now over 96% across all age groups.
Seropositivity estimates for S antibody in blood donors are likely to be higher than would be expected in the general population and this probably reflects the fact that donors are more likely to be vaccinated. Seropositivity estimates for N antibody will underestimate the proportion of the population previously infected due to (i) blood donors are potentially less likely to be exposed to natural infection than age matched individuals in the general population (ii) waning of the N antibody response over time and (iii) recent observations from UKHSA surveillance data that N antibody levels are lower in individuals who acquire infection following 2 doses of vaccination. These lower N antibody responses in individuals with breakthrough infections (post-vaccination) compared to primary infection likely reflect the shorter and milder infections in these patients. Patients with breakthrough infections do have significant increases in S antibody levels consistent with boosting of their antibody levels.
One of the reasons this data indicates so much of the gap being plugged is that their data for people with antibodies caused by infection demonstrates that younger people, who are less liekly to be vaccinated, have had the highest levels of infection, especially once the Delta wave happened. But thats also considered to have been true right from the start of the pandemic, younger people were in harms way for all manner of reasons including having more social contacts, and a rather large proportion of the older population successfully hid from the virus in the first few waves. Although I suppose younger people are also more likely to generate higher antibody levels which show up for longer. Anyway here is one of the charts about that from the same report:
Previously when this subject came up I disagreed with littlebabyjesus about the extent of assumptions we could make in regards how many unvaccinated people had not yet been infected either. Thats partly down to the limitations of the blood donor data as already discussed, I prefer to leave a bit more wiggle room in my assumptions about this. But given the scale of the Omicron wave, reality will already have moved to become closer now to what littlebabyjesus assumed about this weeks ago.
We might be able to further refine our sense of how many unvaccinated, previously uninfected people remain in the population by keeping an eye on data about the vaccine status of people who have been hospitalised or died over a recent period. Such data, which tends to cover a 4 week period, is a bit laggy and wont be covering a 'mostly Omicron' period yet, but I will fish the latest version of it out anyway at some point on Friday. Actually its in the same report I already mentioned, a few pages earlier. Although if we use it for that purpose, we'll be making an assumption that this is those peoples first infection, which isnt necessarily the case. And there are plenty of deaths of vaccinated people in it which demonstrate that the immunity wall has its limits, especially as people get older. It doesnt currently offer info about whether they had a booster either.