Thursday, December 16, 2021

The Best Synthesis Of The Data On Omicron I've Read So Far...

TheData
AreVille


I know I've gone to this well a number of times already but I can't emphasize enough the fantastic job that Dr. Eric Topol of the Scripps Institute is doing keeping up to date with all the COVID data. 

This is particularly true in the case of the Omicron variant of the virus. 

Topol has written a really great longform piece that lays it all out in straightforward language and his conclusions are all backstopped by data that matter.

The piece I'm referring to is a couple of days old now but still very relevant - you should really read it in its entirety - it will only take you a few minutes.

Here are the take home messages that I have gleaned:

1) Vaccine Effectiveness
Two doses of Pfizer gives reduced protection against symptomatic infection (34%) five months after the second shot while a boost takes it back up to 75% compared to the Delta variant (60%/95). However, it is important to realize that symptomatic infection does not appear to be tracking with disease severity (see #4, below).


2) Transmissibility
Household transmission is approximately three fold higher compared to Delta.

3) Prior SARS-Cov-2 infection
The levels of antibodies in the blood of folks who have been previously infected with the virus that can neutralize (i.e. whack) the Omicron variant are low. This likely explains why the rate of folks reinfected by Omicron that have had prior Covid has been high in both South Africa and the UK.  However 'hybrid' immunity for folks who have been both vaccinated and have had prior infection looks to be solid

4) Milder Severity of Disease
This is a point that was brought up by reader Gordie in response to a previous post.  Clearly, the proportion of hospitalizations to cases is down with Omicron compared to Delta and that's a good thing. However, it is not clear why this is the case and if it is intrinsic to the Omicron variant form of the virus itself or if it's due to the fact that lots of folks now have at least some form of immunity to the virus writ large, especially T-cell immunity which is an additional immunological tool that is separate (but works coordinately with) the antibodies produced by B-cells. Topol points out that we really won't know about this until the sample size gets large enough that we can parse out  folks over 60 who have never been infected and have never been vaccinated. Of course, in most Western countries that number is quite small proportionately. 

5) The Curve Thing, Again.
Even if Omicron is significantly less virulent (say even 10X less so than Delta) it could still lead to truly problematic crunches for health care systems that are already running near or over capacity given its potential to induce an enormous number of infections worldwide in a short period of time.


_______
Having said all of the above, it is important to keep in mind how far we have come re: tools for mitigation since this time last year. And that includes mitigating against Omicron. As for that new thing in the toolbox, the rapid antigen test, that hasn't been widely rolled out in British Columbia yet?...Well, much more knowledgeable folks than me on this topic are all for getting that wider roll out going, and fast...Mr. Dix said yesterday that an announcement should come early next week... There may be more on this and maybe the booster rollout also, at a health briefing by Mr. Dix and Dr. Henry tomorrow (although it may be focussed on gathering size restrictions).
Sorry about the delay for the promised post on how the antiviral treatments from Pfizer and Merck work...It's coming, just really busy with the end of term rush these days...The punchline - they don't rely on an immune response to work and thus the immune evasive component of the Omicron variant is not a factor.


.

4 comments:

Gordie said...

I heard on the news today that Omicron replicated 70 times faster in the windpipe (?) but 10 (?) times less rapidly in the lungs (compared to delta?), which may be a partial explanation why Omicron may be less serious.

The details of my previous statement might be incorrect but I got the gist of what I heard right. Sorry, I wasn't expecting to repeat what I heard.

I'm disappointed in the province's response to self test kits and boosters. I'm coming up to 6 months since my second dose and I haven't heard anything about getting my booster yet. Why not expedite boosters? Surely it doesn't matter if I get a booster 2 weeks early. And just get the kits out without all the hand wringing and drama.

RossK said...

You called it right Gordie, based on the data so far - it's why I gave you the shout out in the post!

Re: the situation in lung epithelium, the Gupta lab from Cambridge thinks they might have determined the reason - poor viral/cell membrane fusion...Their thread, with data are....here.

(for the record, while, as I've said many times, I'm not an immunologist I do have considerable experience with the technology they used - 3D organoids - to run their infectivity/fusion tests)

I hear you re: rapid tests and boosters in BC...I got the impression from today's briefing that they are ramping up but it does seem a little overly cautious regarding the timeline (although it's clear that rapid tests are only really useful right before you visit folks so if they get them to us by late next week that would be useful for the holidays).

.

JP said...

thank you the wonderful intel!

RossK said...

You're very welcome JP....The thing that has changed since a week ago is that there are better data now showing what look like lower hospitalization rates, in direct head-to-head same time after infection situations, with Omicron vs. Delta...Will update on that soon, but you can find this stuff at ETopol's twittmachine feed.


.