Four in five people in the UK now have antibodies to coronavirus, according to figures from the Office for National Statistics (ONS).
Antibodies are considered a sign of immunity against Covid-19 as they are produced when a person gets a vaccine or recovers after contracting the virus.
Numbers released on Wednesday revealed 80.3 per cent of adults in England have antibodies to Covid-19.
Levels are similar in Wales (82.7 per cent) and Northern Ireland (79.9 per cent) but considerably lower in Scotland (72.6 per cent).
The figures come from a nationally representative survey of finger-prick blood tests which look for a Covid-specific immune response. The survey was taken on the third week of May – the figures are the most up-to-date numbers provided by the government body.
They reveal that more than 95 per cent of people aged 65 and over now have antibodies to the virus. This cohort accounts for 89 per cent of all Covid deaths in England and Wales.
Antibody levels among people aged 50 to 64 are now around 90 per cent after the people at the bottom of this age bracket, the last priority vaccine group outlined by the JCVI, became eligible for their jabs on March 17.
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The age group to see the biggest jump in antibody levels was those between 35 and 49. In the first week of May, less than two thirds of people this age (65.8 per cent) had antibodies. But two weeks later, this figure was 77.6 per cent.
The data does not show an increase in antibody levels for people aged 16 to 24 and only half of people in this age group have antibodies.
The majority of these young people likely gained their immunity from previous infection with coronavirus, as only 22.8 per cent of them had received a vaccine.
“Antibodies continued to increase in those aged between 25 and 49 years,” the ONS said, as antibodies are now detected in 58.9 per cent of people this age, driven by first doses.
This lack of immunity among young adults is now being addressed by the Government with over-25s becoming able to book their inoculations on Tuesday.
The ONS data records the results of blood tests given out between May 17 and May 23, when the Indian variant was already running rampant in parts of the country, specifically the North West – including Bolton and Blackburn with Darwen.
The North West is now one of the most well-protected areas in England with 80.0 per cent antibody coverage. It is only topped by the East Midlands (80.2 per cent), which also saw large Indian variant outbreaks in Leicester and Nottingham.
The North West also has the greatest percentage of second doses administered, at 51.3 per cent, up from 39.9 per cent of the region’s population two weeks beforehand.
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The ONS measures antibodies because “there is a clear pattern between vaccination and testing positive for Covid-19 antibodies”, but it said the system is not perfect.
For example, other immune system tools are also involved in fighting off an infection which are not measured by the tests.
Also, antibody levels decrease slowly over time, and eventually drop to such a low number that they can not be detected by the blood tests.
However, these low levels are believed to still be adequate for fighting off the coronavirus if a person were to come into contact with SARS-CoV-2.
A recent study from UCL published in the Lancet found people who have previously caught Covid-19 are protected from reinfection for at least ten months.
The new ONS figures on antibodies build on other statistics published on Monday which found the proportion of people dying of Covid in the UK is at the lowest point since before the first lockdown was enforced in March 2020.
Just 0.9 per cent of deaths registered in the week ending May 28 were related to Covid, a total of 106 compared to 10,977 all-cause fatalities.