Thursday, December 09, 2021

The Omicron Uncertainty Principle

Credit NIAID


It was just 2 weeks ago today that we saw the initial South African NICD Statement On B.1.1.529 Variant, and while we've learned a good deal about the (now dubbed) Omicron variant over the past 14 days, it is still too soon to say with certainty how big of an impact it will have. 

Of course, that hasn't stopped a lot of people from making definitive statements.  Even before the data has come in, many are either hyping the Omicron threat or down-playing it. I wish I had that much confidence in my own ability to see the future.

The news over the past 48 hours that Omicron has at least one significant sibling lineage (see Proposal to split B.1.1.529 to incorporate a newly characterised sibling lineage on CoV-Lineages) - one without the signature SGTF (S-gene target failure) of the first Omicron variant - adds yet another level of uncertainty.

This (proposed) BA.2 sub-lineage has already been detected in multiple countries (Canada, Australia, South Africa, etc.) - but we don't yet have a very good handle on its spread - or how it compares with the original Omicron (BA.1) or Delta variant.

A lot of hope is pinned on early reports from South Africa that Omicron appears to produce milder illness than Delta. And I hope that is true. But we need to see a lot more data, from more places than just South Africa, before we can comfortably assume such.  

And even then, viruses evolve, and what is milder today could pick up new virulence inducing  mutations down the road. 

What does seem apparent, at least of the first Omicron variant, is that it is outperforming Delta in places like the UK, South Africa, and Denmark.  Yesterday the UK warned it could become the dominant strain in that country within a month. 

Yesterday, Pfizer-Biontech released preliminary data indicating that two shots of their mRNA vaccine isn't very protective against Omicron, but that a 3rd - booster - shot increases its effectiveness 25-fold.  How long that enhanced protection lasts remains under investigation. 

Wednesday, December 08, 2021 - 06:54 am
  • Preliminary laboratory studies demonstrate that three doses of the Pfizer-BioNTech COVID-19 Vaccine neutralize the Omicron variant (B.1.1.529 lineage) while two doses show significantly reduced neutralization titers
  • Data indicate that a third dose of BNT162b2 increases the neutralizing antibody titers by 25-fold compared to two doses against the Omicron variant; titers after the booster dose are comparable to titers observed after two doses against the wild-type virus which are associated with high levels of protection
  • As 80% of epitopes in the spike protein recognized by CD8+ T cells are not affected by the mutations in the Omicron variant, two doses may still induce protection against severe disease
  • The companies continue to advance the development of a variant-specific vaccine for Omicron and expect to have it available by March in the event that an adaption is needed to further increase the level and duration of protection – with no change expected to the companies’ four billion dose capacity for 2022
While roughly 42% of the world's population is considered `fully vaccinated', only about 4% have had a booster shot, which opens the door for a lot of potential Omicron transmission in 2022.  Hopefully, those with one or two COVID shots will have some protection against serious illness, but how much is unknown. 

There are a lot of moving parts to our coronavirus pandemic, with new factors being introduced into the mix all the time.  What we do know about Omicron (BA.1 or BA.2) is based on surveillance data that - by definition - is already outdated by the time it is collected and collated.  

It doesn't take a Heisenberg to realize that we can't know exactly where Omicron is headed based on our limited snapshot of where it was days, or even weeks ago.  We also can't assume that something else won't change - or even replace - Omicron in the months to come. 

I know people want answers. But good science takes time. 

The threat (or lack, thereof) posed by Omicron will become clearer in the months ahead. While some early reports on Omicron have been reassuring, we still have a lot of Delta to deal with, and the potential return of seasonal influenza as well. 

Which means, for now at least, we still have to deal with our COVID pandemic one wave at a time.