One in seven people in England had coronavirus antibodies in mid-January

Around one in seven people in England — the equivalent of 8.6million — had coronavirus antibodies by mid-January, a major surveillance study revealed today.

The Office for National Statistics (ONS) tested the blood of more than 1,300 people across the country and found 15.3 per cent tested positive for antibodies — up from 10 per cent in December. The proportion was as high as 21 per cent in London. 

Antibodies are substances made by the immune system in response to infection or vaccinations which defend against viruses. The presence of them in the blood generally means someone has either partial or total immunity against catching a disease again.  

But the figures could easily be an under-estimate because antibody levels fade over time and some people won’t ever develop any. Scientists believe most people have high levels of antibodies for six months after an infection but to what extend they fade after then remains a mystery because there has not been a long enough time to follow up. 

The true size of the pandemic is a mystery because millions of infected people were not tested during the height of the crisis last spring. If the ONS results are accurate, it would suggest Covid has an infection-fatality rate (IFR) of around 1.26 per cent, given there have been…