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The Office for National Statistics (ONS) have released the latest report from the COVID-19 infection survey, looking at antibody and vaccination data for the UK.
Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:
“Today’s ONS bulletin on antibody and vaccination levels in the UK, based on findings from the Coronavirus Infection Survey (CIS), is the latest in a regular fortnightly series and takes the data up to 24 October. These are useful figures. In a sense, these latest results don’t tell us much that couldn’t have been deduced from previous data on vaccinations and on infections, but it’s still very important to use them to check that nothing untoward or unexpected has happened. Particularly on antibodies, the CIS results come from blood tests on people aged 16 and over from a representative sample of households across the country, so they are not subject to some of the potential biases that might affect other data sources.
“The antibody test whose results are reported here is one that detects antibodies that could come either from a previous infection, or from vaccination, or both. Since spring this year, the CIS has been testing blood samples for two separate types of antibody that (in principle at least) should be able to distinguish between antibodies from a natural infection and antibodies from vaccination, but no results from those tests have been published yet.
“ONS report that the percentage of the adult population (aged 16 and over) who tested positive for antibodies increased in the most recent week (18-24 October) in three of the four UK nations, though perhaps not in Northern Ireland. It might have been more appropriate to say that the percentage really hasn’t changed much since the previous bulletin. As with any findings from survey data, there is an inevitable statistical margin of error in the estimates. That margin of error is wider in the three countries other than England, simply because fewer antibody tests are carried out in those other three countries. Allowing for those margins of error, it’s not really clear that the percentages testing positive for antibodies have definitely increased, even in England – but the percentage who would test positive does remain high in every one of the four UK countries, with current estimates over 90% in all four countries and in all nine English regions.
“The general pattern of vaccinations and antibody positivity is similar in three of the UK countries, but slightly different in Northern Ireland. It depends on age, as you’d expect because infection levels and the availability of vaccination have varied with age. A slightly over-simplified summary for England, Wales, and Scotland is as follows. The percentage of people who have had two (or more) vaccine doses is very high for all age groups aged 35 and over. In the 25-34 age group, the percentage who have had at least one vaccine dose is also pretty high, and the percentage who have had two doses is also quite high (85-87%) but rather lower than in older age groups. In the youngest age group in these results, 16-24, the percentage who have had at least one vaccine dose is somewhat lower than the other age groups, a little over 80%. But vaccines have been available for a shorter time for that age groups, particularly for its youngest members. Because of that, a smaller proportion, ranging from 47% to 51%, had been double jabbed by the week ending 24 October. No results are available for the under 16s, because they are not tested for antibodies in the CIS.
“However, the estimated percentage of that youngest age group, 16-24, who would test positive for antibodies, is very high, indeed higher than the percentage for most of the older age groups in these three countries and in Northern Ireland too. Indeed the estimated antibody positivity percentage for 16-24 year olds is about 96% in England, Wales and Scotland, and indeed slightly higher (over 97%) in Northern Ireland. Doubtless, despite the relatively low vaccination rate (so far) in this age group, antibody levels are high because there have been so many infections in people of those ages, particularly recently.
“Estimated antibody positivity has remained high in age groups over 24, up to people in their 40s and 50s, in England, Wales and Scotland. Positivity in older people, particularly in the over 70s, had fallen back a bit, but in recent weeks has risen again, quite possibly because of the availability of booster jabs.
“The position in Northern Ireland is not a lot different from in the other three countries in many respects, though generally the proportion of people who have had two vaccine doses is rather lower. ONS point out that there are signs of a slow decline in antibody positivity in the 70 and over age group in Northern Ireland, which, unlike in the other three countries, has not shown recent signs of increasing again. But the statistical margin of error on the Northern Ireland estimates is considerably wider than in the other countries, because fewer people are tested for antibodies there, so we shouldn’t read too much into these possible different in trends.
“I’m no virologist or vaccinologist, but I should remind you that ONS explain in some detail that testing positive for antibodies is not the same thing as being immune from an infection by SARS-CoV-2. There are other aspects of immunity other than those directly related to antibodies, and ONS also point out that a negative antibody test does not mean that one definitely has no antibodies at all, only that the level of antibodies in the blood is below the threshold used for the test.”
Prof Paul Hunter, Professor in Medicine, UEA, said:
“This is the latest in approximately monthly reports on the proportion of the UK population that are positive for Anti Spike protein antibodies. This test cannot distinguish between antibodies generated by vaccine or by immunisation. Whilst the proportion of people antibody positive remains very high in all age groups they have been falling in older age groups in recent months reflecting what we know about waning immunity in people who have their immunisations sooner. However, there is a very clear uptick in the rate of positive tests in all people over 50 and especially in people over 75 in the most recent data into the week ending 18th October. This is one of the first signs that the booster campaign is indeed boosting antibody levels and so immunity. This is consistent with routine data showing a more rapid decline in daily infections in the oldest age groups.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
Prof Kevin McConway: “I am a Trustee of the SMC and a member of its Advisory Committee. I am also a member of the Public Data Advisory Group, which provides expert advice to the Cabinet Office on aspects of public understanding of data during the pandemic. My quote above is in my capacity as an independent professional statistician.”
None others received.