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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:
“The latest fortnightly ONS bulletin on antibody and vaccination levels in the UK community population, based on the ONS Covid-19 Infection Survey (CIS), takes the data up to 13 August for antibodies and 8 August for vaccinations. On antibodies against the SARS-CoV-2 virus that causes Covid-19, ONS say that the percentage of adults (16 and over) who would have tested positive for antibodies “remained high”. That’s true, it’s over 90% in each of the four countries, but I think it’s also fair to say that it has changed very little in any of the four UK countries over the past week or two. The level of antibody positivity in the population is a balance between several things. The antibody test results reported here do not distinguish between antibodies arising from vaccination and those arising when someone is naturally infected. So the positivity rate can increase because of more infections, more vaccinations, or both. However, it can also decrease because antibodies can ‘wane’ – that is, the level of antibodies in the blood can decrease over time until eventually, in some people, they cannot be detected by the test. (I’m not a vaccinologist or immunologist, but ONS do make it clear in their bulletin that immunity from Covid-19 depends on more than antibody levels.) There is certainly some evidence in these figures that the percentages in older age groups who are positive for antibodies have fallen, particularly in the oldest age groups (who were vaccinated first, generally). I should mention, though, that even in the oldest group (aged 80+, or 70+ for Northern Ireland where the data cannot be so finely grained because the sample size is smaller), over 80% would test positive for antibodies in each of the four UK countries.
“In the other direction, there has been some increase in antibody positivity in the youngest age groups, and overall that seems to have roughly cancelled out the falls in antibody positivity in the older age groups. The increase in positivity in young people could be because more of them have been vaccinated, though in fact the vaccination data for the youngest age group (16-24) do not show much of an increase in the most recent week or two. But it could also be because of new infections, and since other data from the CIS indicate that infection has been relatively high in this age group, that could well have had more effect on young people’s antibody levels than vaccination. We’d know more about this if ONS published data that distinguished between antibodies arising from vaccinations and antibodies arising from vaccination. ONS stated1 in March that they would start to test the blood samples taken in the CIS for two different types of antibody that, they believed, would allow for a distinction to be made between these two reasons for being antibody positive. I haven’t seen any results from this additional antibody testing yet, and wonder why they are not yet available, as it’s a long time since March. Has something gone wrong with this proposed process?”
Dr James Doidge, Senior Statistician, Intensive Care National Audit & Research Centre (ICNARC); and Honorary Associate Professor, London School of Hygiene and Tropical Medicine, said:
“One interesting finding is that, in England, 85% of 16-24-year-olds now test positive for antibodies, while only 58% have had any dose of a vaccine. From this, we can deduce that at least 65% of unvaccinated 16-24-year-olds would now test positive for antibodies and therefore have been previously infected (the true % is certainly higher as not everyone who is vaccinated tests positive for antibodies). Does vaccination still provide some benefit for people with antibodies from prior infection? Most studies suggest yes. Do the risks of vaccination outweigh those (reduced) benefits? Perhaps but this is less clear, especially in groups who were at low risk of poor outcome even prior to their infection. What are the implications for vaccine passports? Any system for requiring vaccination should at least consider the role of infection-acquired immunity and the implications of having already survived infection for an individual’s risk-benefit equation.”
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.