22 Dec 2021 Episode 208 Omicron part 1

Wed, 12/22/2021 - 21:12

Episode 208 Omicron

Ep 208-1 : Bekliz finds a somewhat lower analytical sensitivity for omicron in 7Ag-detection assays:

I) Panbio COVID-19 Ag Rapid test device (Abbott); II) Standard 69 Q COVID-19 Ag (SD Biosensor/Roche); III) Sure Status (Premier Medical Corporation), the three latter being WHO-EUL approved and thus of high global public health relevance,

IV) 2019-nCoV Antigen test (Wondfo); V) Beijng Tigsun Diagnostics Co. Ltd (Tigsun); VI) Onsite COVID-19 Ag Rapid Test (CTK Biotech); VII) ACON biotech (Flowflex), several of them

being on the waiting list for WHO-EUL approval.

This analysis is based on virus culture supernatant and needs to be confirmed in clinical studies.  It is still possible that intrinsic lower sensitivity is compensated by a higher viral load in real samples.

Ep 208-2: Ofra shows that a fresh booster (after 2 doses many months earlier) increases protection against confirmed infection by 3.7 (95% CI: 2.7 to 5.2) fold compared to a fresh 2-dose vaccine

This study compared two different age groups: 16-18 eligible for booster and 12-14 eligible for first two doses around the same time. 

Infections are presumably mostly delta, but the neutralizing antibodies after the booster were superior in neutralization assay to antibodies after a second dose against both Delta and Omicron.

Ep 208-3: Laurie SARS-CoV-2 variant exposures (by infection or vaccination) elicit antibody  responses with differential cross-neutralization of established and emerging strains including Delta and Omicron.


Matrix of normalized neutralization titers for seven different variant pseudoviruses (rows) neutralized by seven different pools of individual sera grouped by exposure (columns).

Data is represented as a heat map of the Log2 fold-change in NT50 (top left of each box) and NT90 (bottom right of each box) of each variant relative to D614G pseudovirus.


Positive Log2 fold-change (blue) indicates an increase in neutralization titer for that variant relative to D614G pseudovirus, while negative Log2 fold change (red) indicates a decrease relative to D614G.


Clearly, beta and omicron viruses are poorly neutralized by sera from double vaccinated individuals, but sensitivity to neutralization of beta and omicron is better in case of infection + 2-dose vaccination or 3-dose vaccination.

Ep 208-4:  A first sign from London that hospitalization risk by Omicron may be lower than with Delta.

  1. Full report nr 50:
  • Reduction of any attendance 20-25 % and for at least 1 day hospitalization by 40-45 %.
  • A previous infection reduces the risk of any hospitalisation by approximately 50%
  • Complex picture for vaccination (Table 3)

Unvaccinated cases have somewhat lower risk of hospitalisation with Omicron versus Delta, though the magnitude of this reduction drops when under ascertainment of reinfections is accounted for.

Cases vaccinated with Pfizer or Moderna for doses 1 and 2 have a similar or higher risk of hospitalisation with Omicron compared with Delta, while cases vaccinated with AstraZeneca for their primary vaccine series tend to have a lower risk of hospitalisation relative to Delta.  

(The effect of booster is not very clear, but we are looking at very low numbers)

  • Importantly: These reductions must be balanced against the larger risk of infection with Omicron, due to the reduction in protection provided by both vaccination and natural infection
  1. Press communication (more easy to read)


Ep 208-5: Robert Kock Institute: advice with regard to containment of omicron

• Maximum contact restrictions

• Maximum infection preventive measures

• Maximum speed when vaccinating the population (initial and booster vaccinations)

• Reduction of travel to what is absolutely necessary

• Intensive accompanying communication to understand the measures

Ep 208-6: Danish study on vaccine effectiveness against delta and omicron


VE  against infection is significantly lower against Omicron than Delta and declines rapidly.

VE is re-established upon revaccination with Pfizer vaccine (54.6%), Moderna too few data.


Ep 208-7: Lechmere provides additional evidence for “super-immunity” after breakthrough infection (BTI)  with delta (after full vaccination) as compared to delta infection (without vaccination).

Sera from BTI cross-neutralized several variants of concern and had a somewhat reduced, but still rather high activity against omicron (see p. 13 and 17).


Clearly, these are in vitro data.  It is not clear at what time after infection the sera were taken.  It is also a selected population with rather severe disease in a referral hospital.