Coronavirus (COVID-19): state of the epidemic - 4 February 2022

Resilience: Vaccinations, Antibody Estimates and Variants of Concern

Vaccinations

As at 2 February, 3,302,671 people in Scotland (69% of those aged 12 and above) had received a third vaccine dose or booster, over 4.4 million people had received their first dose and over 4.1 million people had received their second dose.

For daily updates on vaccination figures in Scotland, see Public Health Scotland’s Covid-19 Daily Dashboard. For more analysis on vaccination numbers, see previous publications. Further analysis on vaccinations will be provided in our next weekly release, to align with the publication of antibody estimates.

Antibodies Estimates

Estimated on the proportion of people in the private residential population in Scotland that would test positive for antibodies against SARS-CoV-2 are published by the ONS Covid-19 Infection Survey.

The next scheduled release of antibody and vaccination data from the Covid-19 Infection Survey is 9 February, this will be incorporated into our next weekly release. For information on the most recent estimates, see earlier publications or Covid Infection Survey publications.

Variants of Concern: Omicron Variant

The Omicron variant (parent Pango lineage B.1.1.529) can be separated into three groups: BA.1, BA.2 and BA.3. BA.1 and BA.3 have the 69-70 deletion in the spike protein which gives the S-Gene target failure that has been used to identify the Omicron variant in the recent months, but BA.2 does not^{[55] [56]}. The Omicron variant sub-lineage known as BA.2 has been designated a variant under investigation (VUI-22JAN-01) by the UK Health Security Agency (UKHSA). The original Omicron lineage, BA.1, is dominant in the UK and the proportion of BA.2 cases is currently low. However, there are increasing numbers of BA.2 sequences identified both in the UK and internationally^[57]. Analysis from routine contract tracing data in England from 27 December 2021 to 11 January 2022 indicate higher secondary attack rates amongst contacts of BA.2 households (13.4%) than those for contacts of other Omicron cases (10.3%)^[58].

A new risk assessment for BA.2 lineage carried out by the UK Health Security Agency (UKHSA), established with moderate confidence that BA.2 lineage is showing a growth advantage compared to currently dominant BA.1 lineage in the UK. The advantage has been attributed to increased transmissibility rather than immune evasion however confidence is low due to a small number of BA.2 cases in the analysis^[59]. The Omicron VOC-21NOV-01 risk assessment were reported last week in the State of the Epidemic report.

The UKHSA reported that vaccine effectiveness against symptomatic disease with the Omicron variant is lower compared to the Delta variant, and that it wanes rapidly. The latest data showed effectiveness against symptomatic disease 2-4 weeks after a booster dose ranges from around 60-75% and drops to around 25-40% after 15 or more weeks after the booster. The vaccine effectiveness against hospitalisation with Omicron is high at around 90% after a Pfizer booster (after either primary vaccination course), and dropping to around 75% after ten to fourteen weeks after a Pfizer booster dose. After a Moderna booster (mRNA-1273) vaccine effectiveness against hospitalisation was 90 to 95% up to 9 weeks after vaccination.

The high level of protection against mortality was also restored after the booster dose with vaccine effectiveness at 95% 2 or more weeks following vaccination for those aged 50 and older^[60]. More data on vaccine effectiveness against the Omicron variant can be found in the UKHSA vaccine surveillance reports and it was summarised last week in the State of the Epidemic report.

Preliminary assessment of vaccine effectiveness against symptomatic disease with BA.2 compared to BA.1, showed similar results with BA.1 having an effectiveness of 9% and BA.2 having an effectiveness of 13% after 25 or more weeks following the second dose. These estimates have large overlapping confidence intervals. The booster dose of vaccine restored effectiveness to around 63% for BA.1 and 70% for BA.2 at 2 weeks following a booster vaccine^[61].

There is evidence that there is reduced overall risk of hospitalisation for Omicron compared to Delta^{[62] [63]}, with the most recent estimate of the risk of presentation to emergency care or hospital admission with Omicron was approximately half of that for Delta^[64].