‘Scotland right now is the most vaccinated part of the UK,’ said Nicola Sturgeon on the Sunday Morning show this weekend. And if you look at the UK dashboard figures that’s certainly true. A reported 92 per cent have had a first jab and 68 per cent are boosted compared to 91 per cent and 64 per cent in England. But are these numbers reliable?
If you look at vaccination in certain age groups in Scotland the rollout has been impressive. In the over-50s, 101 per cent are vaccinated, restricted to over-70s it’s 103 per cent. More jabs than people. But how can more than 100 per cent of a population have been vaccinated? Obviously, they can’t. The problem lies in the denominator.
Vaccination rates are based on an absolute number divided by an estimate. We know from electronic records pretty much exactly how many people have been vaccinated. But we don’t know how many people there are to vaccinate, because we don’t know exactly how many people live in the country. The population is therefore estimated using the census, birth and death records and migration estimates. When the vaccination rate is more than 100 per cent it means we have underestimated the true size of the population. That means it is almost impossible to work out how many unvaccinated people there actually are.
Another issue is perhaps more concerning. In England when someone dies (for any reason) they are removed from the vaccine figures and therefore both the numerator and denominator of the vaccine coverage calculation. This doesn’t happen in Scotland. Vaccinated Scots who have died since the rollout began — of which there are tens of thousands — are still included in the figures.
To illustrate the point we can try to estimate the vaccination figure with deaths removed. According to population estimates, there are 469,817 over-75s living in Scotland. Of that group, Scottish government figures claim 104 per cent are vaccinated — some 488,498 people. National Record of Scotland deaths figures show that since 100 percent coverage was reached around 27,000 over-75s have died. Removing that figure shows the number of people jabbed is overstated by nearly five per cent.
Adjusting in this way is too crude a calculation to be reliable but it makes the point that there is a significant overestimation in Scotland’s vaccination rate. That’s not to say vaccine coverage in Scotland isn’t very high, it could still be the highest in the UK. But the reality is we just don’t know the true figures. While underestimating the population might be a feature of English figures too, the issue of the deaths isn’t. If English statisticians are able to remove these death figures, why isn’t the same approach taken in Scotland?
Britain has been a world leader in pandemic data. But differences in devolution are making it increasingly difficult to compare between the different governments — something that’s vital for understanding the impact and effect of Covid restrictions. Politicians must make this clear when making claims about the data.
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