Quote Originally Posted by goji View Post
On 19 April, about 68% of adults had covid antibodies, similar to your figure, so I agree on that (source ONS)

However, on 19 April, 62.5% of adults had one dose of the vaccine, or if we allow 14 days to acquire the antibodies, then on the 5th of April, 59.8% had at least one dose of the vaccine (source gov.co.uk). Far higher than 31%.
You have to distinguish between percentage of adults and percentage of the population. The UK government (unlike most other countries) tends to quote percentage of adults when quoting vaccination rates, but the ourworldindata site helpfully converts this to percentage of population, to bring it in line with other nations.

https://ourworldindata.org/covid-vaccinations

Does one jab give you antibodies - and when? The published data on this is very cautious, saying that one jab 'might' give you antibodies after a fortnight. I took the mid point between first and second jabs as the highest likely number.

Maybe that was over-pessimistic, but even if you take the most optimistic scenario and assume that everyone will test positive for antibodies two weeks after their first jab, it remains hard to construct an argument that vaccination has been the primary source of antibodies, after deducting the number likely to have had them before being jabbed.

An interesting aside to this is the June 14th data, which showed sero-prevalence of 89.8%, indicating that two thirds of those who did not have antibodies eight weeks prior, gained them during that period. As vaccination is not selective, it was not the primary player here, nor were the relatively small (around 200k recorded) number of cases during that period.

What seems to be at play are large numbers of people who received a light encounter with the bug over the winter, a viral load too small to initiate an infection, but large enough to provoke a gradual immune response.

As far as the LoS is concerned, this gives cause for hope. If the current wave is giving enough people a light encounter with the bug, there could well be a high percentage of the population displaying antibodies by year end.