IATA Medical Contact Group - A quick holiday season update

We continue to await more confirmation of the degree of reduced severity of illness (reduced risk of hospitalisation/death) with Omicron.  Any such reduction must be measured against the extremely rapid growth from increased transmissibility of the variant.  But at least in some populations there is evidence of the reduced hospitalisations compared with case numbers.  Some background is available on the UK Health Security Agency site here: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1043807/technical-briefing-33.pdf

There is a new study from Israel that I omitted from the last update, showing that amongst those who had a booster (Pfizer) COVID-19 rates were reduced by 10 times, and severe COVID reduced by 18-21 times depending on age.  Bar-On et al: https://www.nejm.org/doi/pdf/10.1056/NEJMoa2115926?articleTools=true

Cele et al have provided a good summary of what’s understood regarding Omicron, in Nature.  Cele was one of the first authors to publish pre-print information on immune escape of Omicron.
https://www.nature.com/articles/d41586-021-03824-5

Some further studies documenting reduced antibody neutralisation against Omicron, but significant restoration after booster doses:

- Garcia-Beltran et al: https://www.cell.com/cell/fulltext/S0092-8674(21)01496-3#relatedArticles

“Remarkably, neutralization of Omicron was undetectable in most vaccinees. However, individuals boosted with mRNA vaccines exhibited potent neutralization of Omicron, only 4-6-fold lower than wild type, suggesting enhanced cross-reactivity of neutralizing antibody responses.”

- Wang et al: https://www.biorxiv.org/content/10.1101/2021.12.24.474084v1.full.pdf

“The seroconversion rates of neutralizing antibodies were 3.3% (2/60) and 39 95% (57/60) for 2- and 3-dose vaccinees, respectively. For three-dose recipients, the 40 geometric mean neutralization antibody titer (GMT) of Omicron was 15, 16.5-fold 41 lower than that of the ancestral virus (254).”

It was mentioned in an earlier update that most monoclonal antibodies have not proved to be effective as treatments for the Omicron variant – with a few exceptions.  Van Blargan et al  https://doi.org/10.1101/2021.12.15.472828

It is estimated in a JAMA article that vaccinations have prevented 1 million COVID deaths and 10 million hospitalisations in the USA:
https://jamanetwork.com/journals/jama-health-forum/fullarticle/2787531

The US CDC is shortening the recommended time for isolation of people with asymptomatic COVID-19, from 10 days to 5 days (followed by 5 days of mask-wearing when around others):  https://www.cdc.gov/media/releases/2021/s1227-isolation-quarantine-guidance.html

There is some updated info from CDC on the alert levels of countries of origin:

Upgraded to level 4 – Malta, Moldova, Sweden
Moved to level 3 – Argentina (from level 2), Brunei (from level 3)
Reduced to level 2 – Cuba, Gabon, Guatemala
Reduced to level 1 – São Tomé and Príncipe
Moving to unknown – French Polynesia, New Caledonia, Suriname

Note the current bird flu outbreak in Israel which has led to widespread culling of poultry, has not been associated with any reported cases of transmission to humans.

Best wishes,
David Powell
IATA Medical Advisor