UP to one in four adults in Scotland and nearly half of all over 75s now have antibodies to protect them against Covid, according to new estimates.

However, Scotland has the lower prevalence of Covid antibodies of any of the UK nations, according to the latest survey by the Office for National Statistics (ONS).

This is likely to be due a lowest proportion of Scotland's population having been exposed to the virus naturally, through infection, as opposed to any differences in vaccination rate.

The Herald: (Source: ONS) (Source: ONS)

To date, Scotland has given 35 per cent of the total population - and 42% of over 16s - at least one dose of Covid vaccine, compared to 37% in England, 35.6% in Wales, and 33.2% in Northern Ireland.

It takes between two and three weeks after infection or vaccination for the body to make enough antibodies to fight the infection.

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Antibodies remain in the blood at low levels, although these levels can decline over time to the point that tests can no longer detect them.

Having antibodies can help to prevent individuals from getting the same infection again.

The Herald: England currently has the fastest vaccine rollout rate in the UK England currently has the fastest vaccine rollout rate in the UK

The Herald:

The ONS survey compares antibody rates across the UK based on blood samples from a randomly selected cohort of patients in the community, excluding those in hospitals, care homes, or other institutions, such as prisons.

These are extrapolated to give an estimate for the population as a whole in each nation.

The Herald: (Source: ONS) (Source: ONS)

In the 28 days up to March 3, the ONS estimates that 22.3% of the population in Scotland aged 16 and over would have tested positive for Covid antibodies - but suggests the figure could be as high as 24.1%.

This compares to less than 6% between October and November last year, and has doubled since the beginning of the year.

In England, which has the highest antibody estimates of the four nations, an estimated 34.6% of the population has antibodies, compared to 30.5% in Wales, and 31.2% in Northern Ireland. 

Males over 75 in Scotland were estimated to have the highest antibody rate at just under 50%, with females over 75 just slightly lower. 

However, the ONS report cautions that there is "high uncertainty" around the estimates broken down by age group "due to the relatively small number of people included in this analysis", but it adds: "The higher levels of antibodies observed in older age groups likely reflects the high vaccination rate in older people."

The Herald: Close to 50% of over-75s are estimated to have antibodiesClose to 50% of over-75s are estimated to have antibodies

It is possible that many people infected in Scotland during the first wave of coronavirus last year, and not yet vaccinated against it, may not test positive for antibodies but could still have residual protection.

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Studies have shown that antibodies can fade from the bloodstream within three months in some cases, especially where infections were mild, but an absence of antibodies does not necessarily mean someone is no longer protected from the virus.

They may still have protection from T cells and memory B cells, which 'remember' the infection and can generate a fresh wave of antibodies when needed.

The report states: "The presence of antibodies is measured to understand who has had Covid-19 in the past and the impact of vaccinations.

"Once infected, the length of time antibodies remain at detectable levels in the blood is not fully known.

"It is also not yet known how having detectable antibodies, now or at some time in the past, affects the chance of getting Covid-19 again."

The Herald: (Source: ONS) (Source: ONS)

Antibody prevalence was highest overall for the over-80s - the age group prioritised for vaccination - at an estimated 60.9%, and lowest, at just under 15%, for those aged 25 to 34.

The prevalence was slightly higher in females than males - at 25.1% and 19.3% respectively - a pattern that was mirrored across the UK.

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In England, which has the highest antibody estimates of the four nations, an estimated 37.6% of females 31.6% of males within the population were predicted to have some protective immunity from previous infection or vaccination.

In Wales, the estimates were 35.2% for females and 25.5% for males.

In Northern Ireland - where smaller sample sizes make the estimates less reliable - the figures were put at around 33% and 28%.