THREE quarters of children and nearly half of people aged 16 to 24 in Scotland still have no antibodies against Covid, according to the latest surveillance.

Blood samples show that roughly nine in 10 adults over 24 had antibodies against the disease by the beginning of July, but this drops substantially in the youngest age groups suggesting that there is still substantial scope for infections to surge.

Data from the Office for National Statistics shows that, in the week ending July 4, an estimated 88.6 per cent of adults in Scotland - defined as people aged 16 and older - had Covid antibodies.

HeraldScotland: Modelled percentage of adults with Covid antibodies, by nation. Green line indicates antibodies percentage, light blue line first vaccine dose coverage and dark blue second vaccine dose coverageModelled percentage of adults with Covid antibodies, by nation. Green line indicates antibodies percentage, light blue line first vaccine dose coverage and dark blue second vaccine dose coverage

However, the breakdown by age group showed that this fell to just 57.3% among 16 to 24-year-olds.

In every other age group, at least 89% of people were estimated to have antibodies.

This broke down as:

25-34 = 89.1%

35-49 = 92.8%

50-59 = 96%

60-64 = 95.3%

65-69 = 96.4%

70-74 = 94.5%

75-79 = 91.5%

80+ = 89.2%

A separate analysis by Public Health Scotland estimates that just 23.6% of people aged 0-19 in Scotland had antibodies in the week beginning June 21.

It comes amid concerns that slower vaccine uptake in younger Scots could slow the lifting of restrictions, with herd immunity also much harder to achieve after the Joint Committee on Vaccination and Immunisation decided to limit vaccination of 12 to 17-year-olds only to those with serious underlying health conditions, or who live with an adult who is highly vulnerable to Covid.

READ MORE: Covid hospital admissions triple in over-60s 

Professor Devi Sridhar, chair of global public health at Edinburgh University and an advisor on Covid-19 for the Scottish Government, has backed routine vaccination of teenagers ahead of secondary schools returning in mid-August. 

The Pfizer vaccine is already being rolled out to children aged 12 and over in countries including Israel and the United States. 

Reacting to the Public Health Scotland antibody figures, Prof Sridhar tweeted "are we ready for a wave of infection in young people 0-18 (who largely don't have access to the vaccine now)?"

 

HeraldScotland: Percentage of adults with antibodies, by age and nation, where black lines show confidence intervals (longer the line larger the uncertainty of the estimate)Percentage of adults with antibodies, by age and nation, where black lines show confidence intervals (longer the line larger the uncertainty of the estimate)

The ONS surveillance is based on blood samples gathered regularly from thousands of households across the UK, excluding hospital patients and care home residents.

READ MORE: Why are Covid infections still increasing is 85% of Scots adults have antibodies? 

These are screened for Covid antibodies and the data used to extrapolate an estimate for the prevalence of antibodies across the population and age groups as a whole.

HeraldScotland: The PHS data is based on blood samples collected in primary care settings, such as GP practices. Table above shows data for week beginning June 21 (Source: PHS)The PHS data is based on blood samples collected in primary care settings, such as GP practices. Table above shows data for week beginning June 21 (Source: PHS)

The PHS data is based on blood samples gathered from patients in community healthcare settings, such as GP surgeries, with PHS cautioning that "there is uncertainty whether these individuals are representative of the general population".

The presence of antibodies in the blood indicates that a person has either been vaccinated against Covid or has recovered from the infection in the past.

This does not necessarily mean they are immune to the virus, however, as individuals can test positive for antibodies after a single vaccine dose when protection against infection is much lower.

 

 

There is also evidence that people previously infected by non-Delta Covid strains are susceptible to reinfection with the Delta variant, which is responsible for over 99% of cases now in the UK.

READ MORE: Vaccine passport chaos as hundreds jam phones over missing and incorrect details

However, antibodies are also only one element of the immune response which tend to fade over time.

It is possible that people who test negative for antibodies could still have protection from T cells or memory B cells instead.

HeraldScotland:

HeraldScotland: The vast majority of recent infections have already been occurring in younger people who tend to have more contacts and are less likely to be vaccinated than older ScotsThe vast majority of recent infections have already been occurring in younger people who tend to have more contacts and are less likely to be vaccinated than older Scots

Confirmed Covid infections peaked in Scotland in the week ending July 4, and have been falling in all age groups since then.

However, there have been concerns that infections were still showing signs of increasing based on other surveillance methods - such as sewage testing - leading to fears that cases were simply being missed as people failed to get tested. 

This is currently not being reflected in hospital cases though, with the number of patients in hospital with Covid looking to have peaked at 543 on July 15. It is now 488.  

There are also concerns that virus rates will surge again, however, when restrictions are eased further in Scotland from August 9, with schools and colleges returning soon afterwards.