Covid Scotland: Half of Omicron cases in young adults

The first known Omicron outbreak in Scotland was linked to a private event on November 20 involving residents from Greater Glasgow and Lanarkshire, with six cases subsequently traced to a Steps concert at the SSE Hydro in Glasgow on November 22.

A total of 108 have been confirmed in Scotland so far.

Source: Public Health Scotland

Of the 71 Omicron cases confirmed through genomic sequencing by December 5, PHS said 34 (48 per cent) were found in people aged 20 to 39.

This same age group accounted for just 24% of all Covid cases detected in Scotland between November 1 and December 5.

READ MORE: What have we learned about Omicron so far - and how will scientists unravel the rest?

To date, no Omicron cases have been detected in Scotland in anyone aged 70 or older, but four males aged 65 to 69 have tested positive for the new variant.

In its latest report on the epidemic, PHS said it is "not aware of any hospitalisations" involving the highly mutated strain so far, but stressed that it "may be too early to observe this outcome".

S-gene dropout cases of Covid became dominant at the beginning of 2021, when the Alpha ('Kent') strain was spreading, but largely disappeared when the Delta strain took off in the UK in May. They are making a comeback now following the rise of Omicron

The report said that Omicron represents a "very small, but rapidly growing" proportion of all Covid cases, with 389 confirmed, highly probable, and possible cases identified in Scotland by December 5.

The prevalence of cases involving the 'S-gene dropout' - a genomic quirk present in the new variant but very rarely found in the dominant Delta strain - is being used to track the spread of Omicron in Scotland.

PHS noted that S gene dropout rates had been "stable and low, at less than 1 in 1000 cases" from July to October, but increased sharply from 0.1% as of November 23 to 3.1% by December 6.

Confirmed and probable/possible Omicron cases, based on genotyping or S-gene dropouts, have risen rapidly in the past two weeks (Source: Public Health Scotland)

It came as the first evidence of reduced vaccine effectiveness against Omicron emerged from studies in South Africa and Germany.

The first, from the Africa Health Research Institute in Durban, used blood plasma from 12 people given a second dose of the Pfizer a month before to test how strong an immune response they were able to mount against Omicron compared to the original Wuhan strain.

Researchers found a 40-fold reduction in the levels of neutralising antibodies - the proteins which bind to the virus surface and block it from infecting cells - in relation to Omicron.

Professor Alex Sigal, who led the study, described this as a "very large drop" which would lead to an increase in breakthrough infections among the double-vaccinated.

However, there was evidence of a stronger antibody response where people had recovered from a prior Covid infection in addition to being fully vaccinated, suggesting the boosters will help.

“A good booster probably would decrease your chance of infection, especially severe infection leading to more severe disease," said Prof Sigal.

"People who haven’t had a booster should get one, and people who have been previously infected should be vaccinated.”

Matched like for like by age, the Covid mortality rate was six times higher among unvaccinated than fully vaccinated individuals in Scotland at the end of November

Meanwhile, a separate lab test in Frankfurt led by virologist Professor Sandra Ciesek, found that the antibody response to Omicron in people triple-vaccinated with Pfizer was 37 times lower compared to that mounted in response to Delta.

In blood samples from people six months on from their second dose of Pfizer, Moderna, or a mixed course of AstraZeneca-Pfizer, the antibody response "was not even measurable", Prof Ciesek added.

"The set of data underscores that it makes sense to develop a vaccine that is adapted to Omicron," she tweeted, adding that no conclusion could be drawn about protection against severe disease.

READ MORE: Restrictions to be reviewed daily amid 10-fold increase in Omicron cases

Cases of Omicron are estimated to be doubling in the UK every two to three days, and it is expected to become the dominant strain within weeks.

Restrictions - including the possible extension of vaccine passports to leisure and hospitality venues - are now being reviewed daily in Scotland amid fears that a combination of increased transmissibility and some vaccine escape could lead to a spike in Covid admissions during winter, at a time when the NHS is already struggling with treatment backlogs and a substantial rise in emergency admissions compared to the beginning of the year. 

Around 10,800 people per week were being admitted from A&E into hospitals at the end of November, compared to fewer than 9,800 per week in January and February

Early hospital data from South Africa has suggested the variant may cause milder disease compared to Delta, but it is unclear whether the same patterns would be replicated in the UK - which has a much older population - or whether admissions data is skewed by higher levels of immunity compared to previous waves and the spread of Omicron infections occurring mainly in younger people.

Professor Andrew Hayward, a member of the UK government's New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) said it was too early to say Omicron is milder than previous variants, and stressed that even if it were its ability to spread much faster than Delta posed a severe danger.

He said: "Say for example it was half as severe as the previous strains, if you have three times as many cases, that’s still more hospitalisations than we would otherwise have had.

“With it increasing so fast you can get a very, very, very high peak and that's what threatens the NHS capacity.”

It comes as separate data from PHS shows that Covid hospital admissions fell by 44% in Scots aged 60 and over during November - the age group prioritised for boosters - compared to 5% for those under 60.

Covid hospital admissions are falling fastest in older age groups, with patients aged 30-39 actually outnumbering those in their 80s at the end of November

Studies have shown that boosters increase protection against infections caused by the Delta strain to more than 90%.

The report also revealed further detail on Covid infections, vaccinations, and outcomes in pregnant women, particularly in relation to stillbirths and neonatal deaths.

READ MORE: Neonatal deaths spike in September 'not linked to Covid'

Between the beginning of the pandemic in March 2020 and October 31 this year, a total of 5,653 Covid infections have been confirmed in Scotland among pregnant women. 

Of these, 927 (16%) were associated with a hospital admission, and 114 (2%) were associated with a critical care admission.

Vaccination coverage remains much lower among expectant mothers, however, with only 43% of women who gave birth in Scotland during October having received at least one Covid vaccine dose compared to 85% of all women aged 18 to 44. 

Of the 4,950 confirmed Covid cases detected during pregnancy since the beginning of the vaccine rollout in December 2020 up to the end of October this year, 3,833 (77%) occurred in unvaccinated women, 567 (11%) in partially vaccinated women, and 550 (11%) in fully vaccinated women.

Among the 104 Covid infections associated with a critical care admission during this period, 102 (98%) occurred in unvaccinated women.

Rates of stillbirths and neonatal deaths were also four times higher soon after Covid infections than vaccinations. 

READ MORE: Antivaxxers are blaming Covid vaccines for neonatal deaths - a lack of transparency won't help

By the end of October this year, a total of 2,986 babies had been born in Scotland whose mother had tested positive for Covid at any stage of pregnancy. 

This included 12 stillbirths and eight infants who died within 28 days of birth - defined as neonatal mortality. 

This puts the rate of perinatal mortality (neonatal deaths and stillbirths combined) at 6.7 per 1000 total births for Covid infections at all stages of pregnancy. 

However, this rose to a rate of 20.5 per 1000 if the mother had tested positive for Covid in the 28 days prior to giving birth. 

There were 10 stillbirths and four neonatal deaths out of 684 babies born in Scotland within 28 days of their mothers' positive Covid test. 

In relation to vaccination, a total of 5,766 babies were born up to October 31 whose mothers had received one or two Covid vaccinations during pregnancy. 

There were 14 stillbirths and 11 neonatal deaths - a perinatal mortality rate of 4.3 per 1000 births. 

Covid cases among pregnant women spiked in August and September, after Scotland lifted pandemic restrictions (Public Health Scotland)

This rate was unchanged in relation to mothers vaccinated within 28 days prior to delivery: there were four neonatal deaths and three stillbirths out of a total of 1,635 infants born within a month of their mothers' vaccination, giving a perinatal mortality rate of 4.3 per 1000 births.    

The PHS report stresses, however, that "it cannot be assumed that deaths following maternal Covid-19 infection or vaccination are related to those events; stillbirth and neonatal death can occur for a wide range of reasons". 

It adds: "It is important to also consider that 6.3 per 1,000 of all births registered in Scotland in 2020 resulted in stillbirth or neonatal death. 

"Vaccination remains the safest and most effective way for women to protect themselves and their babies against Covid 19 infection."